The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 13 |
| 3 | 15 |
| 4 | 74 |
| 5 | 468 |
| 6 | 2036 |
| 7 | 10982 |
| 8 | 53440 |
| 9 | 271596 |
| 10 | 1360466 |
| 11 | 6832459 |
| 12 | 34345485 |
| 13 | 172485648 |
| 14 | 866676017 |
| 15 | 4353899691 |
| 16 | 21873626234 |
| 17 | 109891360736 |
| 18 | 552080909728 |
| 19 | 2773601514082 |
| 20 | 13934283247296 |
| 21 | 70004406947220 |
| 22 | 351694969884786 |
[0,13,15,74,468,2036,10982,53440,271596,1360466, 6832459,34345485,172485648,866676017,4353899691, 21873626234,109891360736,552080909728, 2773601514082,13934283247296,70004406947220, 351694969884786] |