The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 10 |
| 5 | 55 |
| 6 | 66 |
| 7 | 210 |
| 8 | 253 |
| 9 | 666 |
| 10 | 780 |
| 11 | 4851 |
| 12 | 8911 |
| 13 | 15400 |
| 14 | 17766 |
| 15 | 125751 |
| 16 | 303810 |
| 17 | 407253 |
| 18 | 906531 |
| 19 | 1125750 |
| 20 | 2648451 |
| 21 | 5925403 |
| 22 | 6706953 |
| 23 | 15772536 |
| 24 | 22207780 |
| 25 | 50085036 |
| 26 | 78406503 |
| 27 | 438094800 |
| 28 | 1623331710 |
| 29 | 1764803755 |
| 30 | 3437158416 |
[1,3,6,10,55,66,210,253,666,780,4851,8911,15400, 17766,125751,303810,407253,906531,1125750,2648451, 5925403,6706953,15772536,22207780,50085036, 78406503,438094800,1623331710,1764803755, 3437158416] |