The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 58 |
| 5 | 335 |
| 6 | 2261 |
| 7 | 17465 |
| 8 | 152020 |
| 9 | 1473057 |
| 10 | 15730705 |
| 11 | 183571817 |
| 12 | 2324298010 |
| 13 | 31737207034 |
| 14 | 464904410985 |
| 15 | 7272666016725 |
| 16 | 121007866402968 |
| 17 | 2133917906948645 |
| 18 | 39756493513248129 |
| 19 | 780313261631908137 |
| 20 | 16093326774432620874 |
| 21 | 347958942706716524974 |
[1,3,12,58,335,2261,17465,152020,1473057,15730705, 183571817,2324298010,31737207034,464904410985, 7272666016725,121007866402968,2133917906948645, 39756493513248129,780313261631908137, 16093326774432620874,347958942706716524974] |