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 | 9 |
| 6 | 70 |
| 7 | 571 |
| 8 | 4820 |
| 9 | 44676 |
| 10 | 450824 |
| 11 | 4980274 |
| 12 | 59834748 |
| 13 | 778230060 |
| 14 | 10896609768 |
| 15 | 163456629604 |
| 16 | 2615335902176 |
| 17 | 44460874280032 |
| 18 | 800296440705472 |
| 19 | 15205636325496568 |
| 20 | 304112744618157872 |
| 21 | 6386367741011250672 |