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 | 1 |
| 4 | 5 |
| 5 | 16 |
| 6 | 56 |
| 7 | 198 |
| 8 | 699 |
| 9 | 2490 |
| 10 | 8943 |
| 11 | 32355 |
| 12 | 117800 |
| 13 | 431316 |
| 14 | 1587207 |
| 15 | 5867244 |
| 16 | 21777203 |
| 17 | 81127591 |
| 18 | 303240041 |
| 19 | 1136914129 |
| 20 | 4274441613 |
| 21 | 16111746161 |
| 22 | 60873695892 |
| 23 | 230495640009 |
| 24 | 874525192278 |
| 25 | 3324270554675 |
| 26 | 12658405644200 |
| 27 | 48280298159610 |