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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 11 |
| 6 | 30 |
| 7 | 126 |
| 8 | 519 |
| 9 | 1836 |
| 10 | 5877 |
| 11 | 18866 |
| 12 | 65472 |
| 13 | 242463 |
| 14 | 905425 |
| 15 | 3307371 |
| 16 | 11889414 |
| 17 | 42930441 |
| 18 | 157641714 |
| 19 | 586908936 |
| 20 | 2194106568 |
| 21 | 8189323686 |
| 22 | 30541703733 |
| 23 | 114219616809 |
| 24 | 429214875498 |
| 25 | 1619584557885 |
| 26 | 6125465491551 |