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 | 3 |
| 5 | 9 |
| 6 | 34 |
| 7 | 174 |
| 8 | 1128 |
| 9 | 8251 |
| 10 | 63315 |
| 11 | 494175 |
| 12 | 3879370 |
| 13 | 30512736 |
| 14 | 240149088 |
| 15 | 1890487729 |
| 16 | 14883249459 |
| 17 | 117174190329 |
| 18 | 922506823618 |
| 19 | 7262871367566 |
| 20 | 57180440473320 |
| 21 | 450180590519275 |
| 22 | 3544264121625315 |
| 23 | 27903931958216271 |
| 24 | 219687190433359498 |