The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 7 |
| 6 | 31 |
| 7 | 109 |
| 8 | 623 |
| 9 | 2951 |
| 10 | 20641 |
| 11 | 123216 |
| 12 | 1019051 |
| 13 | 7349140 |
| 14 | 70148989 |
| 15 | 593513485 |
| 16 | 6421463423 |
| 17 | 62382094567 |
| 18 | 754405836811 |
| 19 | 8277393686747 |
| 20 | 110644077164479 |
| 21 | 1353422057172923 |
| 22 | 19814920352425441 |
| 23 | 267391099520321166 |
| 24 | 4255291684449288503 |
| 25 | 62800765220575811118 |
[1,1,1,1,3,7,31,109,623,2951,20641,123216,1019051, 7349140,70148989,593513485,6421463423,62382094567, 754405836811,8277393686747,110644077164479, 1353422057172923,19814920352425441, 267391099520321166,4255291684449288503, 62800765220575811118] |