The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 60 |
| 6 | 346 |
| 7 | 2218 |
| 8 | 15444 |
| 9 | 115075 |
| 10 | 908155 |
| 11 | 7535185 |
| 12 | 65374018 |
| 13 | 590579575 |
| 14 | 5537249212 |
| 15 | 53742567000 |
| 16 | 538801229874 |
| 17 | 5570060420573 |
| 18 | 59288164937748 |
| 19 | 648934780013375 |
| 20 | 7295904025820975 |
| 21 | 84174136470742517 |
| 22 | 995682428049720830 |
[1,1,3,12,60,346,2218,15444,115075,908155,7535185, 65374018,590579575,5537249212,53742567000, 538801229874,5570060420573,59288164937748, 648934780013375,7295904025820975, 84174136470742517,995682428049720830] |