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 | 4 |
| 2 | 17 |
| 3 | 72 |
| 4 | 306 |
| 5 | 1305 |
| 6 | 5577 |
| 7 | 23858 |
| 8 | 102108 |
| 9 | 437080 |
| 10 | 1871065 |
| 11 | 8009866 |
| 12 | 34289712 |
| 13 | 146792138 |
| 14 | 628407994 |
| 15 | 2690174883 |
| 16 | 11516466985 |
| 17 | 49301256865 |
| 18 | 211055514017 |
| 19 | 903515089697 |
| 20 | 3867890010850 |
| 21 | 16558188448465 |
| 22 | 70884540117396 |