The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 22 |
| 4 | 105 |
| 5 | 497 |
| 6 | 2431 |
| 7 | 11976 |
| 8 | 59928 |
| 9 | 302816 |
| 10 | 1545660 |
| 11 | 7955132 |
| 12 | 41255625 |
| 13 | 215378364 |
| 14 | 1131134574 |
| 15 | 5972272636 |
| 16 | 31684600709 |
| 17 | 168824599282 |
| 18 | 903080385252 |
| 19 | 4848038120323 |
| 20 | 26110774945462 |
| 21 | 141048622038068 |
| 22 | 764026532321068 |
| 23 | 4149020129689451 |
[1,1,5,22,105,497,2431,11976,59928,302816,1545660, 7955132,41255625,215378364,1131134574,5972272636, 31684600709,168824599282,903080385252, 4848038120323,26110774945462,141048622038068, 764026532321068,4149020129689451] |