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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 46 |
| 4 | 135 |
| 5 | 4540 |
| 6 | 13261 |
| 7 | 444906 |
| 8 | 1299475 |
| 9 | 43596280 |
| 10 | 127335321 |
| 11 | 4271990566 |
| 12 | 12477562015 |
| 13 | 418611479220 |
| 14 | 1222673742181 |
| 15 | 41019652973026 |
| 16 | 119809549171755 |
| 17 | 4019507379877360 |
| 18 | 11740113145089841 |
| 19 | 393870703575008286 |
| 20 | 1150411278669632695 |
| 21 | 38595309442970934700 |