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 | 6 |
| 3 | 15 |
| 4 | 80 |
| 5 | 312 |
| 6 | 1365 |
| 7 | 5712 |
| 8 | 24310 |
| 9 | 102795 |
| 10 | 435744 |
| 11 | 1845360 |
| 12 | 7817849 |
| 13 | 33115680 |
| 14 | 140282310 |
| 15 | 594242103 |
| 16 | 2517255280 |
| 17 | 10663255848 |
| 18 | 45170290605 |
| 19 | 191344398960 |
| 20 | 810547917686 |
| 21 | 3433536019155 |
| 22 | 14544692076096 |
| 23 | 61612304191200 |
| 24 | 260993909055025 |
| 25 | 1105587940064832 |