The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 15 |
| 3 | 130 |
| 4 | 1263 |
| 5 | 13210 |
| 6 | 145254 |
| 7 | 1655566 |
| 8 | 19385489 |
| 9 | 231803136 |
| 10 | 2818714210 |
| 11 | 34749228048 |
| 12 | 433317651224 |
| 13 | 5455934825956 |
| 14 | 69267925684377 |
| 15 | 885756704750960 |
| 16 | 11397912218979769 |
| 17 | 147483397060856046 |
| 18 | 1917785255491649284 |
| 19 | 25047838828467708506 |
| 20 | 328444729414573179950 |
[1,2,15,130,1263,13210,145254,1655566,19385489, 231803136,2818714210,34749228048,433317651224, 5455934825956,69267925684377,885756704750960, 11397912218979769,147483397060856046, 1917785255491649284,25047838828467708506, 328444729414573179950] |