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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 75 |
| 6 | 312 |
| 7 | 1421 |
| 8 | 7016 |
| 9 | 37260 |
| 10 | 211470 |
| 11 | 1275725 |
| 12 | 8142840 |
| 13 | 54776761 |
| 14 | 387022118 |
| 15 | 2863489830 |
| 16 | 22127336720 |
| 17 | 178162416499 |
| 18 | 1491567656472 |
| 19 | 12959459317021 |
| 20 | 116654844101140 |
| 21 | 1086207322942812 |
| 22 | 10447135955448522 |
| 23 | 103654461984288429 |
| 24 | 1059648140522024304 |