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 | 1 |
| 5 | 244 |
| 6 | 6480 |
| 7 | 69798 |
| 8 | 496198 |
| 9 | 2595897 |
| 10 | 10912452 |
| 11 | 38739354 |
| 12 | 121694240 |
| 13 | 342722071 |
| 14 | 887407361 |
| 15 | 2136513884 |
| 16 | 4828507719 |
| 17 | 10332712952 |
| 18 | 21117591802 |
| 19 | 41392701372 |
| 20 | 78248425161 |
| 21 | 143087468105 |
| 22 | 253946607496 |
| 23 | 438734862156 |