| n | a(n) |
|---|---|
| 4 | 12 |
| 5 | 60 |
| 6 | 210 |
| 7 | 630 |
| 8 | 1736 |
| 9 | 4536 |
| 10 | 11430 |
| 11 | 28050 |
| 12 | 67452 |
| 13 | 159588 |
| 14 | 372554 |
| 15 | 859950 |
| 16 | 1965840 |
| 17 | 4456176 |
| 18 | 10026702 |
| 19 | 22412970 |
| 20 | 49806980 |
| 21 | 110100060 |
| 22 | 242220594 |
| 23 | 530578950 |
| 24 | 1157627352 |
| 25 | 2516581800 |
| 26 | 5452594550 |
| 27 | 11777604930 |
| 28 | 25367149836 |
| 29 | 54492396756 |
| 30 | 116769422490 |
| 31 | 249644973150 |
[12,60,210,630,1736,4536,11430,28050,67452,159588, 372554,859950,1965840,4456176,10026702,22412970, 49806980,110100060,242220594,530578950,1157627352, 2516581800,5452594550,11777604930,25367149836, 54492396756,116769422490,249644973150] |