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 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 1 |
| 6 | 5 |
| 7 | 9 |
| 8 | 45 |
| 9 | 160 |
| 10 | 1018 |
| 11 | 6956 |
| 12 | 67704 |
| 13 | 830392 |
| 14 | 13539344 |
| 15 | 288643968 |
| 16 | 8112651795 |
| 17 | 300974046019 |
| 18 | 14796399706863 |
| 19 | 967194378235406 |
| 20 | 84374194347669628 |
| 21 | 9856131011755992817 |
| 22 | 1546820212559671605395 |