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 | 1 |
| 2 | 4 |
| 3 | 18 |
| 4 | 75 |
| 5 | 320 |
| 6 | 1352 |
| 7 | 5733 |
| 8 | 24276 |
| 9 | 102850 |
| 10 | 435655 |
| 11 | 1845504 |
| 12 | 7817616 |
| 13 | 33116057 |
| 14 | 140281700 |
| 15 | 594243090 |
| 16 | 2517253683 |
| 17 | 10663258432 |
| 18 | 45170286424 |
| 19 | 191344405725 |
| 20 | 810547906740 |
| 21 | 3433536036866 |
| 22 | 14544692047439 |
| 23 | 61612304237568 |
| 24 | 260993908980000 |
| 25 | 1105587940186225 |
| 26 | 4683345669678532 |