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 | 18 |
| 3 | 135 |
| 4 | 796 |
| 5 | 4605 |
| 6 | 28926 |
| 7 | 204883 |
| 8 | 1643160 |
| 9 | 14795001 |
| 10 | 147960010 |
| 11 | 1627574751 |
| 12 | 19530917748 |
| 13 | 253901959285 |
| 14 | 3554627468406 |
| 15 | 53319412076715 |
| 16 | 853110593292976 |
| 17 | 14502880086064113 |
| 18 | 261051841549259010 |
| 19 | 4959984989436051511 |
| 20 | 99199699788721190220 |