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 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 39 |
| 4 | 648 |
| 5 | 15465 |
| 6 | 483240 |
| 7 | 18685905 |
| 8 | 861282832 |
| 9 | 46085893011 |
| 10 | 2807152825020 |
| 11 | 191731595897600 |
| 12 | 14510053796849640 |
| 13 | 1205013817282706730 |
| 14 | 108941005329522201360 |
| 15 | 10650027832902977866245 |
| 16 | 1119401271751383414197280 |
| 17 | 125879457463215695125460535 |