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 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 64 |
| 5 | 325 |
| 6 | 1956 |
| 7 | 13699 |
| 8 | 109600 |
| 9 | 986409 |
| 10 | 9864100 |
| 11 | 108505111 |
| 12 | 1302061344 |
| 13 | 16926797485 |
| 14 | 236975164804 |
| 15 | 3554627472075 |
| 16 | 56874039553216 |
| 17 | 966858672404689 |
| 18 | 17403456103284420 |
| 19 | 330665665962403999 |
| 20 | 6613313319248080000 |
| 21 | 138879579704209680021 |
| 22 | 3055350753492612960484 |