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 | 1 |
| 3 | 20 |
| 4 | 102 |
| 5 | 2288 |
| 6 | 3773 |
| 7 | 14232 |
| 8 | 133616 |
| 9 | 119904 |
| 10 | 584517 |
| 11 | 1927900 |
| 12 | 4013432 |
| 13 | 2569296 |
| 14 | 14394518 |
| 15 | 8365192 |
| 16 | 14426496 |
| 17 | 23381600 |
| 18 | 151885575 |
| 19 | 58125708 |
| 20 | 269849564 |
| 21 | 395149888 |
| 22 | 195967551 |
| 23 | 828880856 |
| 24 | 398774464 |
| 25 | 544543680 |
| 26 | 4586626939 |
| 27 | 1018905048 |
| 28 | 1396485648 |