The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 28 |
| 5 | 244 |
| 6 | 2566 |
| 7 | 33438 |
| 8 | 508544 |
| 9 | 8926944 |
| 10 | 176989488 |
| 11 | 3917823216 |
| 12 | 95719041408 |
| 13 | 2559130965312 |
| 14 | 74312569125744 |
| 15 | 2329169772108528 |
| 16 | 78371469374088960 |
| 17 | 2817744760964392704 |
| 18 | 107807187260426164992 |
| 19 | 4373419962377871956736 |
| 20 | 187507942522161269068800 |
[1,1,1,5,28,244,2566,33438,508544,8926944, 176989488,3917823216,95719041408,2559130965312, 74312569125744,2329169772108528,78371469374088960, 2817744760964392704,107807187260426164992, 4373419962377871956736,187507942522161269068800] |