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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 5 |
| 6 | 32 |
| 7 | 134 |
| 8 | 588 |
| 9 | 2335 |
| 10 | 9335 |
| 11 | 36506 |
| 12 | 144263 |
| 13 | 571238 |
| 14 | 2291894 |
| 15 | 9300462 |
| 16 | 38303796 |
| 17 | 160062325 |
| 18 | 679333926 |
| 19 | 2927951665 |
| 20 | 12817221628 |
| 21 | 56974693933 |
| 22 | 257132512297 |
| 23 | 1177882648846 |
| 24 | 5475237760563 |
| 25 | 25818721638720 |
| 26 | 123473772356785 |
| 27 | 598687942799298 |
| 28 | 2942344764127039 |