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 | 0 |
| 3 | 0 |
| 4 | 128 |
| 5 | 6745 |
| 6 | 100332 |
| 7 | 754453 |
| 8 | 3830016 |
| 9 | 15038541 |
| 10 | 49207020 |
| 11 | 140410699 |
| 12 | 360001152 |
| 13 | 846775007 |
| 14 | 1855033964 |
| 15 | 3828109545 |
| 16 | 7507096576 |
| 17 | 14087087961 |
| 18 | 25436160108 |
| 19 | 44395753647 |
| 20 | 75184958080 |
| 21 | 123935571963 |
| 22 | 199389702380 |
| 23 | 313797119069 |
| 24 | 484055619840 |
| 25 | 733144325125 |