The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 73 |
| 5 | 580 |
| 6 | 5601 |
| 7 | 63994 |
| 8 | 844929 |
| 9 | 12647016 |
| 10 | 211616065 |
| 11 | 3914510446 |
| 12 | 79320037281 |
| 13 | 1747219469164 |
| 14 | 41569414869633 |
| 15 | 1062343684252530 |
| 16 | 29023112392093441 |
| 17 | 844101839207139280 |
| 18 | 26038508978625589377 |
| 19 | 849150487829425227094 |
| 20 | 29189561873274715264545 |
[1,1,3,12,73,580,5601,63994,844929,12647016, 211616065,3914510446,79320037281,1747219469164, 41569414869633,1062343684252530,29023112392093441, 844101839207139280,26038508978625589377, 849150487829425227094,29189561873274715264545] |