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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 525 |
| 4 | 3105 |
| 5 | 18939 |
| 6 | 114381 |
| 7 | 693129 |
| 8 | 4195557 |
| 9 | 25405586 |
| 10 | 153820395 |
| 11 | 931359050 |
| 12 | 5639156409 |
| 13 | 34143908573 |
| 14 | 206733865761 |
| 15 | 1251728824798 |
| 16 | 7578945799704 |
| 17 | 45888871327435 |
| 18 | 277847147039527 |
| 19 | 1682304127857000 |
| 20 | 10185986079451152 |