The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 52 |
| 4 | 200 |
| 5 | 2896 |
| 6 | 15392 |
| 7 | 169792 |
| 8 | 1078400 |
| 9 | 10306816 |
| 10 | 72376832 |
| 11 | 639480832 |
| 12 | 4753049600 |
| 13 | 40201179136 |
| 14 | 308548739072 |
| 15 | 2546754076672 |
[0,1,2,52,200,2896,15392,169792,1078400,10306816, 72376832,639480832,4753049600,40201179136, 308548739072,2546754076672] |