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 | 0 |
| 4 | 1 |
| 5 | 2 |
| 6 | 12 |
| 7 | 71 |
| 8 | 481 |
| 9 | 3708 |
| 10 | 32028 |
| 11 | 306723 |
| 12 | 3228804 |
| 13 | 37080394 |
| 14 | 461569226 |
| 15 | 6192527700 |
| 16 | 89102492915 |
| 17 | 1369014167140 |
| 18 | 22373840093040 |
| 19 | 387602212164321 |
| 20 | 7095737193164187 |
| 21 | 136885937242792752 |
| 22 | 2775675888994318366 |
| 23 | 59023506305591628101 |
| 24 | 1313445236142071926488 |