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 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 25 |
| 6 | 102 |
| 7 | 456 |
| 8 | 2219 |
| 9 | 11639 |
| 10 | 65320 |
| 11 | 389533 |
| 12 | 2451393 |
| 13 | 16164044 |
| 14 | 110866328 |
| 15 | 785411383 |
| 16 | 5709898562 |
| 17 | 42358751505 |
| 18 | 319155928942 |
| 19 | 2433165471304 |
| 20 | 18714220718157 |
| 21 | 144885627697659 |
| 22 | 1127182676182780 |
| 23 | 8800901309557829 |