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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 0 |
| 5 | 1 |
| 6 | 20 |
| 7 | 1 |
| 8 | 112 |
| 9 | 1681 |
| 10 | 492 |
| 11 | 27721 |
| 12 | 371624 |
| 13 | 319177 |
| 14 | 13461604 |
| 15 | 171387217 |
| 16 | 319071456 |
| 17 | 11466038689 |
| 18 | 143550642140 |
| 19 | 484491620089 |
| 20 | 15758152572952 |
| 21 | 199089883272217 |
| 22 | 1077471975974484 |
| 23 | 32827750137627457 |
| 24 | 427744154995090256 |
| 25 | 3385134777669637681 |