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 | 1 |
| 2 | 11 |
| 3 | 93 |
| 4 | 794 |
| 5 | 6885 |
| 6 | 60460 |
| 7 | 536155 |
| 8 | 4791323 |
| 9 | 43081973 |
| 10 | 389329652 |
| 11 | 3533047572 |
| 12 | 32174057272 |
| 13 | 293874981603 |
| 14 | 2691171713924 |
| 15 | 24700051833634 |
| 16 | 227150464141969 |
| 17 | 2092620625940629 |
| 18 | 19308393192688804 |
| 19 | 178406554524801820 |
| 20 | 1650535921328322392 |
| 21 | 15287533448476027572 |