The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 15 |
| 6 | 49 |
| 7 | 168 |
| 8 | 598 |
| 9 | 2190 |
| 10 | 8196 |
| 11 | 31208 |
| 12 | 120523 |
| 13 | 470952 |
| 14 | 1858620 |
| 15 | 7397590 |
| 16 | 29660563 |
| 17 | 119689341 |
| 18 | 485721836 |
| 19 | 1981073350 |
| 20 | 8116387242 |
| 21 | 33387024530 |
| 22 | 137840606500 |
| 23 | 570973544293 |
| 24 | 2372291510583 |
| 25 | 9883781844032 |
| 26 | 41284245752344 |
| 27 | 172848651689951 |
| 28 | 725257087734821 |
| 29 | 3049259724163608 |
| 30 | 12844360099623312 |
| 31 | 54199019990087808 |
| 32 | 229077223340016720 |
[1,1,2,5,15,49,168,598,2190,8196,31208,120523, 470952,1858620,7397590,29660563,119689341, 485721836,1981073350,8116387242,33387024530, 137840606500,570973544293,2372291510583, 9883781844032,41284245752344,172848651689951, 725257087734821,3049259724163608, 12844360099623312,54199019990087808, 229077223340016720] |