The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 71 |
| 5 | 466 |
| 6 | 3582 |
| 7 | 31641 |
| 8 | 316171 |
| 9 | 3526606 |
| 10 | 43421978 |
| 11 | 584716386 |
| 12 | 8544649478 |
| 13 | 134622445348 |
| 14 | 2274031087772 |
| 15 | 40987164702945 |
| 16 | 784981384215795 |
| 17 | 15916200367695510 |
| 18 | 340548893413909410 |
| 19 | 7666975604019750630 |
[1,1,3,13,71,466,3582,31641,316171,3526606, 43421978,584716386,8544649478,134622445348, 2274031087772,40987164702945,784981384215795, 15916200367695510,340548893413909410, 7666975604019750630] |