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 | 5 |
| 2 | 21 |
| 3 | 119 |
| 4 | 735 |
| 5 | 4830 |
| 6 | 33253 |
| 7 | 237336 |
| 8 | 1743588 |
| 9 | 13114465 |
| 10 | 100591491 |
| 11 | 784428522 |
| 12 | 6204258970 |
| 13 | 49675571820 |
| 14 | 402013608525 |
| 15 | 3284214703056 |
| 16 | 27055525967324 |
| 17 | 224557688302164 |
| 18 | 1876374953765620 |
| 19 | 15774315150669075 |
| 20 | 133345566025874055 |
| 21 | 1132905339504465590 |
| 22 | 9669675838370401035 |