The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 6 |
| 5 | 9 |
| 6 | 26 |
| 7 | 53 |
| 8 | 146 |
| 9 | 369 |
| 10 | 1002 |
| 11 | 2685 |
| 12 | 7434 |
| 13 | 20441 |
| 14 | 57046 |
| 15 | 159451 |
| 16 | 448686 |
| 17 | 1266081 |
| 18 | 3588002 |
| 19 | 10195277 |
| 20 | 29058526 |
| 21 | 83018783 |
| 22 | 237740670 |
| 23 | 682196949 |
| 24 | 1961331314 |
| 25 | 5648590737 |
| 26 | 16294052602 |
| 27 | 47071590147 |
| 28 | 136171497650 |
| 29 | 394427456121 |
| 30 | 1143839943618 |
| 31 | 3320824711205 |
[1,1,2,3,6,9,26,53,146,369,1002,2685,7434,20441, 57046,159451,448686,1266081,3588002,10195277, 29058526,83018783,237740670,682196949,1961331314, 5648590737,16294052602,47071590147,136171497650, 394427456121,1143839943618,3320824711205] |