| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 6 |
| 4 | 31 |
| 5 | 160 |
| 6 | 856 |
| 7 | 4802 |
| 8 | 28337 |
| 9 | 175896 |
| 10 | 1146931 |
| 11 | 7841108 |
| 12 | 56089804 |
| 13 | 418952508 |
| 14 | 3261082917 |
| 15 | 26403700954 |
| 16 | 221981169447 |
| 17 | 1934688328192 |
| 18 | 17454004213180 |
| 19 | 162765041827846 |
| 20 | 1566915224106221 |
| 21 | 15553364227949564 |
| 22 | 159004783733999787 |
| 23 | 1672432865100333916 |
[0,0,1,6,31,160,856,4802,28337,175896,1146931, 7841108,56089804,418952508,3261082917,26403700954, 221981169447,1934688328192,17454004213180, 162765041827846,1566915224106221, 15553364227949564,159004783733999787, 1672432865100333916] |