n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 28 |
4 | 276 |
5 | 3480 |
6 | 53232 |
7 | 955524 |
8 | 19672320 |
9 | 456803328 |
10 | 11810032896 |
11 | 336463895808 |
12 | 10473959755008 |
13 | 353739038360832 |
14 | 12883270796310528 |
15 | 503352328766459904 |
16 | 21001144899441162240 |
17 | 931963581151516477440 |
18 | 43832663421577452887040 |
19 | 2178029362561822117094400 |
20 | 114014865901176834809333760 |
[1,1,4,28,276,3480,53232,955524,19672320, 456803328,11810032896,336463895808,10473959755008, 353739038360832,12883270796310528, 503352328766459904,21001144899441162240, 931963581151516477440,43832663421577452887040, 2178029362561822117094400, 114014865901176834809333760] |