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 | 2 |
| 2 | 6 |
| 3 | 20 |
| 4 | 70 |
| 5 | 252 |
| 6 | 924 |
| 7 | 1144 |
| 8 | 12870 |
| 9 | 48620 |
| 10 | 184756 |
| 11 | 705432 |
| 12 | 2704156 |
| 13 | 10400600 |
| 14 | 40116600 |
| 15 | 155117520 |
| 16 | 200360130 |
| 17 | 466721244 |
| 18 | 9075135300 |
| 19 | 11781754600 |
| 20 | 137846528820 |
| 21 | 538257874440 |
| 22 | 140273264248 |
| 23 | 8233430727600 |
| 24 | 32247603683100 |