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 | 0 |
| 5 | 1 |
| 6 | 1 |
| 7 | 2 |
| 8 | 5 |
| 9 | 16 |
| 10 | 58 |
| 11 | 264 |
| 12 | 1535 |
| 13 | 10755 |
| 14 | 87973 |
| 15 | 803973 |
| 16 | 8020967 |
| 17 | 86029760 |
| 18 | 983431053 |
| 19 | 11913921910 |
| 20 | 152352965278 |
| 21 | 2050065073002 |
| 22 | 28951233955602 |
| 23 | 428086557232387 |