The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 26 |
| 4 | 225 |
| 5 | 1082 |
| 6 | 18732 |
| 7 | 94586 |
| 8 | 2183340 |
| 9 | 21261783 |
| 10 | 408990252 |
| 11 | 3245265146 |
| 12 | 168549405570 |
| 13 | 1053716696762 |
| 14 | 42565371881772 |
| 15 | 921132763911412 |
| 16 | 26578273409906775 |
| 17 | 260741534058271802 |
| 18 | 20313207979541071938 |
| 19 | 185603174638656822266 |
| 20 | 16066126777466305218690 |
[1,6,26,225,1082,18732,94586,2183340,21261783, 408990252,3245265146,168549405570,1053716696762, 42565371881772,921132763911412,26578273409906775, 260741534058271802,20313207979541071938, 185603174638656822266,16066126777466305218690] |