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 | 21 |
| 3 | 174 |
| 4 | 1509 |
| 5 | 13473 |
| 6 | 122580 |
| 7 | 1129999 |
| 8 | 10518477 |
| 9 | 98644395 |
| 10 | 930607321 |
| 11 | 8821717743 |
| 12 | 83960385396 |
| 13 | 801783097911 |
| 14 | 7678690148647 |
| 15 | 73721697254874 |
| 16 | 709323064431597 |
| 17 | 6837868454315828 |
| 18 | 66028546945097793 |
| 19 | 638555320797561440 |
| 20 | 6183787002091288969 |
| 21 | 59957399899953193063 |