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 | 3 |
| 3 | 15 |
| 4 | 114 |
| 5 | 1242 |
| 6 | 17129 |
| 7 | 284714 |
| 8 | 5526741 |
| 9 | 122592633 |
| 10 | 3057488913 |
| 11 | 84665033543 |
| 12 | 2576896828787 |
| 13 | 85495426794698 |
| 14 | 3070641026296061 |
| 15 | 118685141706060740 |
| 16 | 4911825483278949553 |
| 17 | 216697390123422589527 |
| 18 | 10151899714746097960699 |
| 19 | 503310218588181014061292 |