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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 22 |
| 5 | 340 |
| 6 | 3954 |
| 7 | 44716 |
| 8 | 536858 |
| 9 | 7056252 |
| 10 | 102140970 |
| 11 | 1622267196 |
| 12 | 28090317226 |
| 13 | 526854073564 |
| 14 | 10641328363722 |
| 15 | 230283141084220 |
| 16 | 5315654511587498 |
| 17 | 130370766447282204 |
| 18 | 3385534661270087178 |
| 19 | 92801587312544823804 |
| 20 | 2677687796221222845802 |
| 21 | 81124824998424994578652 |