The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 14 |
| 4 | 64 |
| 5 | 316 |
| 6 | 1728 |
| 7 | 10267 |
| 8 | 65536 |
| 9 | 445375 |
| 10 | 3200000 |
| 11 | 24172676 |
| 12 | 191102976 |
| 13 | 1575167569 |
| 14 | 13492928512 |
| 15 | 119786923326 |
| 16 | 1099511627776 |
| 17 | 10412878353556 |
| 18 | 101559956668416 |
| 19 | 1018460448140640 |
| 20 | 10485760000000000 |
| 21 | 110692335104026963 |
| 22 | 1196683881290399744 |
[1,1,4,14,64,316,1728,10267,65536,445375,3200000, 24172676,191102976,1575167569,13492928512, 119786923326,1099511627776,10412878353556, 101559956668416,1018460448140640, 10485760000000000,110692335104026963, 1196683881290399744] |