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 | 67 |
| 4 | 449 |
| 5 | 3315 |
| 6 | 25963 |
| 7 | 211685 |
| 8 | 1777410 |
| 9 | 15263446 |
| 10 | 133427406 |
| 11 | 1183336278 |
| 12 | 10620959908 |
| 13 | 96292118665 |
| 14 | 880540044576 |
| 15 | 8112042293581 |
| 16 | 75218203558241 |
| 17 | 701439747294225 |
| 18 | 6574348389693202 |
| 19 | 61897799517155325 |
| 20 | 585138783209680944 |
| 21 | 5551797662571097495 |