This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 6 |
| 2 | 72 |
| 3 | 702 |
| 4 | 6480 |
| 5 | 58806 |
| 6 | 530712 |
| 7 | 4780782 |
| 8 | 43040160 |
| 9 | 387400806 |
| 10 | 3486725352 |
| 11 | 31380882462 |
| 12 | 282429005040 |
| 13 | 2541864234006 |
| 14 | 22876787671992 |
| 15 | 205891117745742 |
| 16 | 1853020145805120 |
| 17 | 16677181570526406 |
| 18 | 150094634909578632 |
| 19 | 1350851716510730622 |
| 20 | 12157665455570144400 |
| 21 | 109418989121052006006 |