The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 14 |
| 5 | 45 |
| 6 | 138 |
| 7 | 411 |
| 8 | 1200 |
| 9 | 3454 |
| 10 | 9836 |
| 11 | 27779 |
| 12 | 77938 |
| 13 | 217493 |
| 14 | 604222 |
| 15 | 1672246 |
| 16 | 4613030 |
| 17 | 12689265 |
| 18 | 34817418 |
| 19 | 95320335 |
| 20 | 260436588 |
| 21 | 710278318 |
| 22 | 1933906496 |
| 23 | 5257545599 |
| 24 | 14273273314 |
| 25 | 38699274665 |
| 26 | 104799960058 |
| 27 | 283487736166 |
| 28 | 766045036730 |
| 29 | 2067997219629 |
| 30 | 5577597593466 |
| 31 | 15030365074659 |
| 32 | 40470488092008 |
[0,0,1,4,14,45,138,411,1200,3454,9836,27779,77938, 217493,604222,1672246,4613030,12689265,34817418, 95320335,260436588,710278318,1933906496, 5257545599,14273273314,38699274665,104799960058, 283487736166,766045036730,2067997219629, 5577597593466,15030365074659,40470488092008] |