The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 49 |
| 5 | 381 |
| 6 | 3331 |
| 7 | 32593 |
| 8 | 354033 |
| 9 | 4233673 |
| 10 | 55312291 |
| 11 | 784156341 |
| 12 | 11991160633 |
| 13 | 196749380413 |
| 14 | 3447839233203 |
| 15 | 64266128818921 |
| 16 | 1269511428781921 |
| 17 | 26490929023150353 |
| 18 | 582231094609675843 |
| 19 | 13442728593179726173 |
| 20 | 325265025877909014441 |
| 21 | 8230062097594150286341 |
[0,0,1,7,49,381,3331,32593,354033,4233673, 55312291,784156341,11991160633,196749380413, 3447839233203,64266128818921,1269511428781921, 26490929023150353,582231094609675843, 13442728593179726173,325265025877909014441, 8230062097594150286341] |