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 | 1 |
| 4 | 8 |
| 5 | 76 |
| 6 | 752 |
| 7 | 7728 |
| 8 | 76138 |
| 9 | 683740 |
| 10 | 6016612 |
| 11 | 52483260 |
| 12 | 453461612 |
| 13 | 3873299197 |
| 14 | 32718505462 |
| 15 | 274368261226 |
| 16 | 2287565667766 |
| 17 | 18973561019204 |
| 18 | 156622182476404 |
| 19 | 1287479429817295 |
| 20 | 10545476231546336 |
| 21 | 86101164740284870 |
| 22 | 700977394316933694 |
| 23 | 5692064258367318333 |