The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 21 |
| 3 | 345 |
| 4 | 2603 |
| 5 | 21219 |
| 6 | 166748 |
| 7 | 1344235 |
| 8 | 10913024 |
| 9 | 88366783 |
| 10 | 712584163 |
| 11 | 5745262476 |
| 12 | 46374678582 |
| 13 | 374501872949 |
| 14 | 3023676494284 |
| 15 | 24407465600762 |
| 16 | 197018704356836 |
| 17 | 1590454512178565 |
| 18 | 12839424596411861 |
| 19 | 103648778945160117 |
[21,21,345,2603,21219,166748,1344235,10913024, 88366783,712584163,5745262476,46374678582, 374501872949,3023676494284,24407465600762, 197018704356836,1590454512178565, 12839424596411861,103648778945160117] |