The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 20 |
| 3 | 105 |
| 4 | 755 |
| 5 | 7206 |
| 6 | 86895 |
| 7 | 1264270 |
| 8 | 21399545 |
| 9 | 410288306 |
| 10 | 8742115145 |
| 11 | 204205278908 |
| 12 | 5177537318502 |
| 13 | 141430336450640 |
| 14 | 4138123770051847 |
| 15 | 129084367791600672 |
| 16 | 4276207014911374799 |
| 17 | 149935339089873769895 |
[1,5,20,105,755,7206,86895,1264270,21399545, 410288306,8742115145,204205278908,5177537318502, 141430336450640,4138123770051847, 129084367791600672,4276207014911374799, 149935339089873769895] |