The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 20 |
| 4 | 62 |
| 5 | 204 |
| 6 | 684 |
| 7 | 2312 |
| 8 | 7926 |
| 9 | 27436 |
| 10 | 95572 |
| 11 | 334872 |
| 12 | 1178796 |
| 13 | 4164984 |
| 14 | 14763096 |
| 15 | 52471056 |
| 16 | 186928422 |
| 17 | 667295052 |
| 18 | 2386388356 |
| 19 | 8547855032 |
| 20 | 30661465476 |
| 21 | 110125076328 |
| 22 | 395989755496 |
| 23 | 1425411710064 |
| 24 | 5135888179644 |
| 25 | 18521445768696 |
| 26 | 66847890766152 |
[1,2,6,20,62,204,684,2312,7926,27436,95572,334872, 1178796,4164984,14763096,52471056,186928422, 667295052,2386388356,8547855032,30661465476, 110125076328,395989755496,1425411710064, 5135888179644,18521445768696,66847890766152] |