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 | 3 |
| 2 | 24 |
| 3 | 147 |
| 4 | 816 |
| 5 | 4323 |
| 6 | 22344 |
| 7 | 113907 |
| 8 | 576096 |
| 9 | 2900163 |
| 10 | 14559864 |
| 11 | 72976467 |
| 12 | 365413776 |
| 13 | 1828663203 |
| 14 | 9148098984 |
| 15 | 45754843827 |
| 16 | 228817265856 |
| 17 | 1144215469443 |
| 18 | 5721464767704 |
| 19 | 28608486099987 |
| 20 | 143045917284336 |
| 21 | 715240046774883 |
| 22 | 3576231614934024 |
| 23 | 17881252217848947 |
| 24 | 89406543518781216 |