The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 110 |
| 6 | 632 |
| 7 | 4241 |
| 8 | 32588 |
| 9 | 282319 |
| 10 | 2723367 |
| 11 | 28956324 |
| 12 | 336500792 |
| 13 | 4243680123 |
| 14 | 57726145630 |
| 15 | 842549831398 |
| 16 | 13134803320582 |
| 17 | 217825262451008 |
| 18 | 3829135527898758 |
| 19 | 71124557422108254 |
| 20 | 1391954866602464562 |
| 21 | 28628532870485795846 |
| 22 | 617344251641100690905 |
[1,2,6,23,110,632,4241,32588,282319,2723367, 28956324,336500792,4243680123,57726145630, 842549831398,13134803320582,217825262451008, 3829135527898758,71124557422108254, 1391954866602464562,28628532870485795846, 617344251641100690905] |