The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 40 |
| 4 | 224 |
| 5 | 360 |
| 6 | 2016 |
| 7 | 47616 |
| 8 | 174592 |
| 9 | 293760 |
| 10 | 524160 |
| 11 | 1571328 |
| 12 | 1782144 |
| 13 | 3485664 |
| 14 | 134209536 |
| 15 | 282977280 |
| 16 | 492101632 |
| 17 | 746444160 |
| 18 | 1459956960 |
| 19 | 1684126080 |
| 20 | 1716728832 |
| 21 | 4428914688 |
| 22 | 27298252800 |
| 23 | 41233360896 |
| 24 | 376591138560 |
| 25 | 719045268480 |
| 26 | 1622308746240 |
[1,4,40,224,360,2016,47616,174592,293760,524160, 1571328,1782144,3485664,134209536,282977280, 492101632,746444160,1459956960,1684126080, 1716728832,4428914688,27298252800,41233360896, 376591138560,719045268480,1622308746240] |