The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 299 |
| 3 | 4071 |
| 4 | 55643 |
| 5 | 761795 |
| 6 | 10437240 |
| 7 | 142860055 |
| 8 | 1956512289 |
| 9 | 26790134422 |
| 10 | 366852068404 |
| 11 | 5023461594972 |
| 12 | 68788552129955 |
| 13 | 941953214288271 |
| 14 | 12898594994181355 |
| 15 | 176626393130327608 |
| 16 | 2418626153744793468 |
[21,299,4071,55643,761795,10437240,142860055, 1956512289,26790134422,366852068404,5023461594972, 68788552129955,941953214288271,12898594994181355, 176626393130327608,2418626153744793468] |