The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 35 |
| 5 | 236 |
| 6 | 2037 |
| 7 | 21695 |
| 8 | 277966 |
| 9 | 4198635 |
| 10 | 73558135 |
| 11 | 1475177880 |
| 12 | 33495959399 |
| 13 | 853167955357 |
| 14 | 24182881926558 |
| 15 | 757554068775721 |
| 16 | 26068954296880361 |
| 17 | 980202973852646786 |
| 18 | 40079727064364154465 |
| 19 | 1774594774575753650941 |
| 20 | 84756211791797266285252 |
[1,1,2,7,35,236,2037,21695,277966,4198635, 73558135,1475177880,33495959399,853167955357, 24182881926558,757554068775721,26068954296880361, 980202973852646786,40079727064364154465, 1774594774575753650941,84756211791797266285252] |