n | a(n) |
---|---|
0 | 1 |
1 | 2 |
2 | 4 |
3 | 8 |
4 | 20 |
5 | 40 |
6 | 120 |
7 | 520 |
8 | 1560 |
9 | 8840 |
10 | 26520 |
11 | 185640 |
12 | 769080 |
13 | 5383560 |
14 | 28455960 |
15 | 199191720 |
16 | 1166694360 |
17 | 8166860520 |
18 | 61834801080 |
19 | 432843607560 |
20 | 3771922865880 |
21 | 26403460061160 |
22 | 275350369209240 |
23 | 1927452584464680 |
24 | 21201978429111480 |
25 | 171543280017356520 |
[1,2,4,8,20,40,120,520,1560,8840,26520,185640, 769080,5383560,28455960,199191720,1166694360, 8166860520,61834801080,432843607560,3771922865880, 26403460061160,275350369209240,1927452584464680, 21201978429111480,171543280017356520] |