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 | 1 |
| 2 | 5 |
| 3 | 24 |
| 4 | 146 |
| 5 | 1215 |
| 6 | 13431 |
| 7 | 186816 |
| 8 | 3130436 |
| 9 | 61291125 |
| 10 | 1371742105 |
| 11 | 34522712136 |
| 12 | 964626945558 |
| 13 | 29621465864627 |
| 14 | 991330604373851 |
| 15 | 35906022352657920 |
| 16 | 1399219698628043016 |
| 17 | 58367293868445147657 |
| 18 | 2594796705962971336125 |
| 19 | 122463905297217627859000 |