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 | 3 |
| 2 | 12 |
| 3 | 55 |
| 4 | 315 |
| 5 | 2243 |
| 6 | 19378 |
| 7 | 198363 |
| 8 | 2358860 |
| 9 | 32060736 |
| 10 | 491393909 |
| 11 | 8398281337 |
| 12 | 158541018923 |
| 13 | 3279307650137 |
| 14 | 73808041476439 |
| 15 | 1796794875356409 |
| 16 | 47063878147374980 |
| 17 | 1320276655048586177 |
| 18 | 39504980013582635300 |
| 19 | 1256210676237601811305 |
| 20 | 42313074100060933324771 |