Sólo una lista; lo puse en un factoring de comandos con un límite, por lo que es rápido, aquí me dijo investigar los factores primos de a $n! + 3 n$ sólo hasta 10.000. Como se puede ver, la descomposición en factores primos de a $n$ influencias de los factores primos de a $n! + 3 n.$ Como otros han dicho, también puede utilizar las condiciones de $\bmod 4$ sin conocer la totalidad de la factorización de nada. Nota cómo, por $n \geq 7,$ si $n$ no es divisible por $3$, entonces el "RESULTADO" es divisible por $3$ pero no $9,$, por lo que no puede ser un cuadrado. Oh, por el gran número, tuve que escribir cdot en el caso de que me quería convertir al Látex más tarde. Molesto.
Bien, leer a través de una copia impresa, sólo el apoyo de Jack de la idea de que el número es descartado por cualquiera de las $3$ o por un primer dividiendo $n$ si $n = 3 k^2.$
1 = 1 OUTCOME = 2^2
2 = 2 OUTCOME = 2^3
3 = 3 OUTCOME = 3 cdot 5
4 = 2^2 OUTCOME = 2^2 cdot 3^2
5 = 5 OUTCOME = 3^3 cdot 5
6 = 2 * 3 OUTCOME = 2 cdot 3^2 cdot 41
7 = 7 OUTCOME = 3 cdot 7 cdot 241
8 = 2^3 OUTCOME = 2^3 cdot 3 cdot 41^2
9 = 3^2 OUTCOME = 3^3 cdot mbox{BIG}
10 = 2 * 5 OUTCOME = 2 cdot 3 cdot 5 cdot 73 cdot 1657
11 = 11 OUTCOME = 3 cdot 11 cdot 17 cdot mbox{BIG}
12 = 2^2 * 3 OUTCOME = 2^2 cdot 3^2 cdot mbox{BIG}
13 = 13 OUTCOME = 3 cdot 13 cdot 103 cdot mbox{BIG}
14 = 2 * 7 OUTCOME = 2 cdot 3 cdot 7 cdot 19 cdot 67 cdot 1021 cdot 1597
15 = 3 * 5 OUTCOME = 3^2 cdot 5 cdot 43 cdot mbox{BIG}
16 = 2^4 OUTCOME = 2^4 cdot 3 cdot 19 cdot 89 cdot mbox{BIG}
17 = 17 OUTCOME = 3 cdot 17 cdot 821 cdot 3089 cdot mbox{BIG}
18 = 2 * 3^2 OUTCOME = 2 cdot 3^3 cdot mbox{BIG}
19 = 19 OUTCOME = 3 cdot 19 cdot 47 cdot 89 cdot mbox{BIG}
20 = 2^2 * 5 OUTCOME = 2^2 cdot 3 cdot 5 cdot 37 cdot 467 cdot mbox{BIG}
21 = 3 * 7 OUTCOME = 3^2 cdot 7 cdot 29 cdot mbox{BIG}
22 = 2 * 11 OUTCOME = 2 cdot 3 cdot 11 cdot mbox{BIG}
23 = 23 OUTCOME = 3 cdot 23 cdot 283 cdot mbox{BIG}
24 = 2^3 * 3 OUTCOME = 2^3 cdot 3^2 cdot mbox{BIG}
25 = 5^2 OUTCOME = 3 cdot 5^2 cdot mbox{BIG}
26 = 2 * 13 OUTCOME = 2 cdot 3 cdot 13 cdot mbox{BIG}
27 = 3^3 OUTCOME = 3^4 cdot 37 cdot mbox{BIG}
28 = 2^2 * 7 OUTCOME = 2^2 cdot 3 cdot 7 cdot 1873 cdot mbox{BIG}
29 = 29 OUTCOME = 3 cdot 29 cdot 2011 cdot mbox{BIG}
30 = 2 * 3 * 5 OUTCOME = 2 cdot 3^2 cdot 5 cdot 331 cdot 2939 cdot mbox{BIG}
31 = 31 OUTCOME = 3 cdot 31 cdot mbox{BIG}
32 = 2^5 OUTCOME = 2^5 cdot 3 cdot 73 cdot 311 cdot 5197 cdot mbox{BIG}
33 = 3 * 11 OUTCOME = 3^2 cdot 11 cdot 157 cdot 317 cdot mbox{BIG}
34 = 2 * 17 OUTCOME = 2 cdot 3 cdot 17 cdot mbox{BIG}
35 = 5 * 7 OUTCOME = 3 cdot 5 cdot 7 cdot 43 cdot mbox{BIG}
36 = 2^2 * 3^2 OUTCOME = 2^2 cdot 3^3 cdot 251 cdot mbox{BIG}
37 = 37 OUTCOME = 3 cdot 37 cdot mbox{BIG}
38 = 2 * 19 OUTCOME = 2 cdot 3 cdot 19 cdot 163 cdot mbox{BIG}
39 = 3 * 13 OUTCOME = 3^2 cdot 13 cdot mbox{BIG}
40 = 2^3 * 5 OUTCOME = 2^3 cdot 3 cdot 5 cdot mbox{BIG}
41 = 41 OUTCOME = 3 cdot 41 cdot 109 cdot 1483 cdot mbox{BIG}
42 = 2 * 3 * 7 OUTCOME = 2 cdot 3^2 cdot 7 cdot mbox{BIG}
43 = 43 OUTCOME = 3 cdot 43 cdot mbox{BIG}
44 = 2^2 * 11 OUTCOME = 2^2 cdot 3 cdot 11 cdot mbox{BIG}
45 = 3^2 * 5 OUTCOME = 3^3 cdot 5 cdot 2293 cdot mbox{BIG}
46 = 2 * 23 OUTCOME = 2 cdot 3 cdot 23 cdot 127 cdot mbox{BIG}
47 = 47 OUTCOME = 3 cdot 47 cdot 97 cdot 967 cdot mbox{BIG}
48 = 2^4 * 3 OUTCOME = 2^4 cdot 3^2 cdot 89 cdot 137 cdot mbox{BIG}
49 = 7^2 OUTCOME = 3 cdot 7^2 cdot mbox{BIG}
50 = 2 * 5^2 OUTCOME = 2 cdot 3 cdot 5^2 cdot 149 cdot mbox{BIG}
51 = 3 * 17 OUTCOME = 3^2 cdot 17 cdot 131 cdot mbox{BIG}
52 = 2^2 * 13 OUTCOME = 2^2 cdot 3 cdot 13 cdot 4219 cdot mbox{BIG}
53 = 53 OUTCOME = 3 cdot 53 cdot 347 cdot 1489 cdot 7253 cdot mbox{BIG}
54 = 2 * 3^3 OUTCOME = 2 cdot 3^4 cdot 4339 cdot mbox{BIG}
55 = 5 * 11 OUTCOME = 3 cdot 5 cdot 11 cdot mbox{BIG}
56 = 2^3 * 7 OUTCOME = 2^3 cdot 3 cdot 7 cdot 593 cdot mbox{BIG}
57 = 3 * 19 OUTCOME = 3^2 cdot 19 cdot 71 cdot 223 cdot mbox{BIG}
58 = 2 * 29 OUTCOME = 2 cdot 3 cdot 29 cdot mbox{BIG}
59 = 59 OUTCOME = 3 cdot 59 cdot mbox{BIG}
60 = 2^2 * 3 * 5 OUTCOME = 2^2 cdot 3^2 cdot 5 cdot 1039 cdot mbox{BIG}
61 = 61 OUTCOME = 3 cdot 61 cdot 211 cdot mbox{BIG}
62 = 2 * 31 OUTCOME = 2 cdot 3 cdot 31 cdot mbox{BIG}
63 = 3^2 * 7 OUTCOME = 3^3 cdot 7 cdot 1787 cdot mbox{BIG}
64 = 2^6 OUTCOME = 2^6 cdot 3 cdot mbox{BIG}
65 = 5 * 13 OUTCOME = 3 cdot 5 cdot 13 cdot mbox{BIG}
66 = 2 * 3 * 11 OUTCOME = 2 cdot 3^2 cdot 11 cdot mbox{BIG}
67 = 67 OUTCOME = 3 cdot 67 cdot 71 cdot mbox{BIG}
68 = 2^2 * 17 OUTCOME = 2^2 cdot 3 cdot 17 cdot 8753 cdot mbox{BIG}
69 = 3 * 23 OUTCOME = 3^2 cdot 23 cdot 733 cdot mbox{BIG}
70 = 2 * 5 * 7 OUTCOME = 2 cdot 3 cdot 5 cdot 7 cdot mbox{BIG}
71 = 71 OUTCOME = 3 cdot 71 cdot 953 cdot mbox{BIG}
72 = 2^3 * 3^2 OUTCOME = 2^3 cdot 3^3 cdot 1601 cdot mbox{BIG}
73 = 73 OUTCOME = 3 cdot 73 cdot mbox{BIG}
74 = 2 * 37 OUTCOME = 2 cdot 3 cdot 37 cdot mbox{BIG}
75 = 3 * 5^2 OUTCOME = 3^2 cdot 5^2 cdot 199 cdot 211 cdot 373 cdot mbox{BIG}
76 = 2^2 * 19 OUTCOME = 2^2 cdot 3 cdot 19 cdot mbox{BIG}
77 = 7 * 11 OUTCOME = 3 cdot 7 cdot 11 cdot mbox{BIG}
78 = 2 * 3 * 13 OUTCOME = 2 cdot 3^2 cdot 13 cdot mbox{BIG}
79 = 79 OUTCOME = 3 cdot 79 cdot 113 cdot mbox{BIG}
80 = 2^4 * 5 OUTCOME = 2^4 cdot 3 cdot 5 cdot 191 cdot 4583 cdot mbox{BIG}
81 = 3^4 OUTCOME = 3^5 cdot mbox{BIG}
82 = 2 * 41 OUTCOME = 2 cdot 3 cdot 41 cdot 139 cdot mbox{BIG}
83 = 83 OUTCOME = 3 cdot 83 cdot mbox{BIG}
84 = 2^2 * 3 * 7 OUTCOME = 2^2 cdot 3^2 cdot 7 cdot mbox{BIG}
85 = 5 * 17 OUTCOME = 3 cdot 5 cdot 17 cdot mbox{BIG}
86 = 2 * 43 OUTCOME = 2 cdot 3 cdot 43 cdot mbox{BIG}
87 = 3 * 29 OUTCOME = 3^2 cdot 29 cdot mbox{BIG}
88 = 2^3 * 11 OUTCOME = 2^3 cdot 3 cdot 11 cdot 211 cdot 4639 cdot mbox{BIG}
89 = 89 OUTCOME = 3 cdot 89 cdot 97 cdot mbox{BIG}
90 = 2 * 3^2 * 5 OUTCOME = 2 cdot 3^3 cdot 5 cdot 1373 cdot mbox{BIG}
91 = 7 * 13 OUTCOME = 3 cdot 7 cdot 13 cdot 1571 cdot mbox{BIG}
92 = 2^2 * 23 OUTCOME = 2^2 cdot 3 cdot 23 cdot mbox{BIG}
93 = 3 * 31 OUTCOME = 3^2 cdot 31 cdot mbox{BIG}
94 = 2 * 47 OUTCOME = 2 cdot 3 cdot 47 cdot mbox{BIG}
95 = 5 * 19 OUTCOME = 3 cdot 5 cdot 19 cdot mbox{BIG}
96 = 2^5 * 3 OUTCOME = 2^5 cdot 3^2 cdot 179 cdot mbox{BIG}
97 = 97 OUTCOME = 3 cdot 97 cdot mbox{BIG}
98 = 2 * 7^2 OUTCOME = 2 cdot 3 cdot 7^2 cdot mbox{BIG}
99 = 3^2 * 11 OUTCOME = 3^3 cdot 11 cdot mbox{BIG}
100 = 2^2 * 5^2 OUTCOME = 2^2 cdot 3 cdot 5^2 cdot mbox{BIG}
101 = 101 OUTCOME = 3 cdot 101 cdot 1031 cdot 1277 cdot 2999 cdot mbox{BIG}
102 = 2 * 3 * 17 OUTCOME = 2 cdot 3^2 cdot 17 cdot 7933 cdot mbox{BIG}
103 = 103 OUTCOME = 3 cdot 103 cdot mbox{BIG}
104 = 2^3 * 13 OUTCOME = 2^3 cdot 3 cdot 13 cdot mbox{BIG}
105 = 3 * 5 * 7 OUTCOME = 3^2 cdot 5 cdot 7 cdot 3677 cdot mbox{BIG}
106 = 2 * 53 OUTCOME = 2 cdot 3 cdot 53 cdot 5569 cdot mbox{BIG}
107 = 107 OUTCOME = 3 cdot 107 cdot 2393 cdot mbox{BIG}
108 = 2^2 * 3^3 OUTCOME = 2^2 cdot 3^4 cdot 829 cdot mbox{BIG}
109 = 109 OUTCOME = 3 cdot 109 cdot 173 cdot 2287 cdot mbox{BIG}
110 = 2 * 5 * 11 OUTCOME = 2 cdot 3 cdot 5 cdot 11 cdot mbox{BIG}
111 = 3 * 37 OUTCOME = 3^2 cdot 37 cdot mbox{BIG}
112 = 2^4 * 7 OUTCOME = 2^4 cdot 3 cdot 7 cdot 173 cdot mbox{BIG}
113 = 113 OUTCOME = 3 cdot 113 cdot mbox{BIG}
114 = 2 * 3 * 19 OUTCOME = 2 cdot 3^2 cdot 19 cdot mbox{BIG}
115 = 5 * 23 OUTCOME = 3 cdot 5 cdot 23 cdot mbox{BIG}
116 = 2^2 * 29 OUTCOME = 2^2 cdot 3 cdot 29 cdot 1051 cdot 3617 cdot mbox{BIG}
117 = 3^2 * 13 OUTCOME = 3^3 cdot 13 cdot 1753 cdot mbox{BIG}
118 = 2 * 59 OUTCOME = 2 cdot 3 cdot 59 cdot mbox{BIG}
119 = 7 * 17 OUTCOME = 3 cdot 7 cdot 17 cdot 1439 cdot mbox{BIG}
120 = 2^3 * 3 * 5 OUTCOME = 2^3 cdot 3^2 cdot 5 cdot 149 cdot 4049 cdot mbox{BIG}
121 = 11^2 OUTCOME = 3 cdot 11^2 cdot 127 cdot mbox{BIG}
122 = 2 * 61 OUTCOME = 2 cdot 3 cdot 61 cdot mbox{BIG}
123 = 3 * 41 OUTCOME = 3^2 cdot 41 cdot 5179 cdot mbox{BIG}
124 = 2^2 * 31 OUTCOME = 2^2 cdot 3 cdot 31 cdot 857 cdot 1789 cdot mbox{BIG}
125 = 5^3 OUTCOME = 3 cdot 5^3 cdot mbox{BIG}
126 = 2 * 3^2 * 7 OUTCOME = 2 cdot 3^3 cdot 7 cdot 997 cdot 2243 cdot mbox{BIG}
127 = 127 OUTCOME = 3 cdot 127 cdot 1187 cdot 2153 cdot mbox{BIG}
128 = 2^7 OUTCOME = 2^7 cdot 3 cdot 569 cdot mbox{BIG}
129 = 3 * 43 OUTCOME = 3^2 cdot 43 cdot mbox{BIG}
130 = 2 * 5 * 13 OUTCOME = 2 cdot 3 cdot 5 cdot 13 cdot mbox{BIG}
131 = 131 OUTCOME = 3 cdot 131 cdot 191 cdot mbox{BIG}
132 = 2^2 * 3 * 11 OUTCOME = 2^2 cdot 3^2 cdot 11 cdot mbox{BIG}
133 = 7 * 19 OUTCOME = 3 cdot 7 cdot 19 cdot 743 cdot mbox{BIG}
134 = 2 * 67 OUTCOME = 2 cdot 3 cdot 67 cdot 373 cdot 577 cdot mbox{BIG}
135 = 3^3 * 5 OUTCOME = 3^4 cdot 5 cdot mbox{BIG}
136 = 2^3 * 17 OUTCOME = 2^3 cdot 3 cdot 17 cdot 1889 cdot mbox{BIG}
137 = 137 OUTCOME = 3 cdot 137 cdot 7907 cdot mbox{BIG}
138 = 2 * 3 * 23 OUTCOME = 2 cdot 3^2 cdot 23 cdot mbox{BIG}
139 = 139 OUTCOME = 3 cdot 139 cdot 6133 cdot mbox{BIG}
140 = 2^2 * 5 * 7 OUTCOME = 2^2 cdot 3 cdot 5 cdot 7 cdot mbox{BIG}
141 = 3 * 47 OUTCOME = 3^2 cdot 47 cdot mbox{BIG}
142 = 2 * 71 OUTCOME = 2 cdot 3 cdot 71 cdot mbox{BIG}
143 = 11 * 13 OUTCOME = 3 cdot 11 cdot 13 cdot mbox{BIG}
144 = 2^4 * 3^2 OUTCOME = 2^4 cdot 3^3 cdot mbox{BIG}
145 = 5 * 29 OUTCOME = 3 cdot 5 cdot 29 cdot mbox{BIG}
146 = 2 * 73 OUTCOME = 2 cdot 3 cdot 73 cdot 2659 cdot mbox{BIG}
147 = 3 * 7^2 OUTCOME = 3^2 cdot 7^2 cdot 179 cdot mbox{BIG}
148 = 2^2 * 37 OUTCOME = 2^2 cdot 3 cdot 37 cdot 211 cdot 271 cdot 2677 cdot mbox{BIG}
149 = 149 OUTCOME = 3 cdot 149 cdot mbox{BIG}
150 = 2 * 3 * 5^2 OUTCOME = 2 cdot 3^2 cdot 5^2 cdot mbox{BIG}
151 = 151 OUTCOME = 3 cdot 151 cdot mbox{BIG}
152 = 2^3 * 19 OUTCOME = 2^3 cdot 3 cdot 19 cdot 1213 cdot mbox{BIG}
153 = 3^2 * 17 OUTCOME = 3^3 cdot 17 cdot 1289 cdot mbox{BIG}
154 = 2 * 7 * 11 OUTCOME = 2 cdot 3 cdot 7 cdot 11 cdot 827 cdot 3463 cdot mbox{BIG}
155 = 5 * 31 OUTCOME = 3 cdot 5 cdot 31 cdot mbox{BIG}
156 = 2^2 * 3 * 13 OUTCOME = 2^2 cdot 3^2 cdot 13 cdot mbox{BIG}
157 = 157 OUTCOME = 3 cdot 157 cdot 379 cdot mbox{BIG}
158 = 2 * 79 OUTCOME = 2 cdot 3 cdot 79 cdot 6037 cdot mbox{BIG}
159 = 3 * 53 OUTCOME = 3^2 cdot 53 cdot 1733 cdot 5407 cdot mbox{BIG}
160 = 2^5 * 5 OUTCOME = 2^5 cdot 3 cdot 5 cdot 4003 cdot mbox{BIG}
161 = 7 * 23 OUTCOME = 3 cdot 7 cdot 23 cdot mbox{BIG}
162 = 2 * 3^4 OUTCOME = 2 cdot 3^5 cdot 331 cdot mbox{BIG}
163 = 163 OUTCOME = 3 cdot 163 cdot mbox{BIG}
164 = 2^2 * 41 OUTCOME = 2^2 cdot 3 cdot 41 cdot 271 cdot mbox{BIG}
165 = 3 * 5 * 11 OUTCOME = 3^2 cdot 5 cdot 11 cdot mbox{BIG}
166 = 2 * 83 OUTCOME = 2 cdot 3 cdot 83 cdot 239 cdot mbox{BIG}
167 = 167 OUTCOME = 3 cdot 167 cdot mbox{BIG}
168 = 2^3 * 3 * 7 OUTCOME = 2^3 cdot 3^2 cdot 7 cdot mbox{BIG}
169 = 13^2 OUTCOME = 3 cdot 13^2 cdot 373 cdot 439 cdot 1489 cdot 4799 cdot mbox{BIG}
170 = 2 * 5 * 17 OUTCOME = 2 cdot 3 cdot 5 cdot 17 cdot mbox{BIG}
171 = 3^2 * 19 OUTCOME = 3^3 cdot 19 cdot 317 cdot mbox{BIG}
172 = 2^2 * 43 OUTCOME = 2^2 cdot 3 cdot 43 cdot mbox{BIG}
173 = 173 OUTCOME = 3 cdot 173 cdot mbox{BIG}
174 = 2 * 3 * 29 OUTCOME = 2 cdot 3^2 cdot 29 cdot 883 cdot 3539 cdot mbox{BIG}
175 = 5^2 * 7 OUTCOME = 3 cdot 5^2 cdot 7 cdot 211 cdot mbox{BIG}
176 = 2^4 * 11 OUTCOME = 2^4 cdot 3 cdot 11 cdot 6899 cdot mbox{BIG}
177 = 3 * 59 OUTCOME = 3^2 cdot 59 cdot mbox{BIG}
178 = 2 * 89 OUTCOME = 2 cdot 3 cdot 89 cdot mbox{BIG}
179 = 179 OUTCOME = 3 cdot 179 cdot 239 cdot 3593 cdot mbox{BIG}
180 = 2^2 * 3^2 * 5 OUTCOME = 2^2 cdot 3^3 cdot 5 cdot mbox{BIG}
181 = 181 OUTCOME = 3 cdot 181 cdot 653 cdot mbox{BIG}
182 = 2 * 7 * 13 OUTCOME = 2 cdot 3 cdot 7 cdot 13 cdot 5581 cdot mbox{BIG}
183 = 3 * 61 OUTCOME = 3^2 cdot 61 cdot 337 cdot 5749 cdot mbox{BIG}
184 = 2^3 * 23 OUTCOME = 2^3 cdot 3 cdot 23 cdot mbox{BIG}
185 = 5 * 37 OUTCOME = 3 cdot 5 cdot 37 cdot 571 cdot mbox{BIG}
186 = 2 * 3 * 31 OUTCOME = 2 cdot 3^2 cdot 31 cdot 1901 cdot mbox{BIG}
187 = 11 * 17 OUTCOME = 3 cdot 11 cdot 17 cdot mbox{BIG}
188 = 2^2 * 47 OUTCOME = 2^2 cdot 3 cdot 47 cdot mbox{BIG}
189 = 3^3 * 7 OUTCOME = 3^4 cdot 7 cdot 3089 cdot mbox{BIG}
190 = 2 * 5 * 19 OUTCOME = 2 cdot 3 cdot 5 cdot 19 cdot mbox{BIG}
191 = 191 OUTCOME = 3 cdot 191 cdot mbox{BIG}
192 = 2^6 * 3 OUTCOME = 2^6 cdot 3^2 cdot 4973 cdot mbox{BIG}
193 = 193 OUTCOME = 3 cdot 193 cdot mbox{BIG}
194 = 2 * 97 OUTCOME = 2 cdot 3 cdot 97 cdot 839 cdot mbox{BIG}
195 = 3 * 5 * 13 OUTCOME = 3^2 cdot 5 cdot 13 cdot mbox{BIG}
196 = 2^2 * 7^2 OUTCOME = 2^2 cdot 3 cdot 7^2 cdot 947 cdot mbox{BIG}
197 = 197 OUTCOME = 3 cdot 197 cdot 421 cdot mbox{BIG}
198 = 2 * 3^2 * 11 OUTCOME = 2 cdot 3^3 cdot 11 cdot 5653 cdot mbox{BIG}
199 = 199 OUTCOME = 3 cdot 199 cdot 761 cdot 1259 cdot mbox{BIG}
200 = 2^3 * 5^2 OUTCOME = 2^3 cdot 3 cdot 5^2 cdot 433 cdot mbox{BIG}
jagy@phobeusjunior:~$