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 | 2 |
| 3 | 18 |
| 4 | 146 |
| 5 | 1170 |
| 6 | 9362 |
| 7 | 74898 |
| 8 | 599186 |
| 9 | 4793490 |
| 10 | 38347922 |
| 11 | 306783378 |
| 12 | 2454267026 |
| 13 | 19634136210 |
| 14 | 157073089682 |
| 15 | 1256584717458 |
| 16 | 10052677739666 |
| 17 | 80421421917330 |
| 18 | 643371375338642 |
| 19 | 5146971002709138 |
| 20 | 41175768021673106 |
| 21 | 329406144173384850 |
| 22 | 2635249153387078802 |
| 23 | 21081993227096630418 |