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 | 9 |
| 4 | 102 |
| 5 | 870 |
| 6 | 6744 |
| 7 | 50421 |
| 8 | 371676 |
| 9 | 2731569 |
| 10 | 20113005 |
| 11 | 148752507 |
| 12 | 1106207331 |
| 13 | 8274878880 |
| 14 | 62263100994 |
| 15 | 471138360426 |
| 16 | 3584051515209 |
| 17 | 27399942354822 |
| 18 | 210432444531798 |
| 19 | 1622954350900455 |
| 20 | 12565580096217270 |
| 21 | 97634810663895132 |
| 22 | 761110656740387865 |
| 23 | 5951117699678438271 |