The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 81 |
| 5 | 598 |
| 6 | 4859 |
| 7 | 41748 |
| 8 | 374820 |
| 9 | 3475284 |
| 10 | 33053399 |
| 11 | 320869264 |
| 12 | 3167899567 |
| 13 | 31721907390 |
| 14 | 321494911644 |
| 15 | 3292220700520 |
| 16 | 34018798556265 |
| 17 | 354312456839426 |
| 18 | 3716173628641396 |
| 19 | 39220841304052510 |
| 20 | 416264662788000213 |
[1,3,12,81,598,4859,41748,374820,3475284,33053399, 320869264,3167899567,31721907390,321494911644, 3292220700520,34018798556265,354312456839426, 3716173628641396,39220841304052510, 416264662788000213] |