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 | 24 |
| 4 | 110 |
| 5 | 496 |
| 6 | 2156 |
| 7 | 9216 |
| 8 | 38742 |
| 9 | 160032 |
| 10 | 664532 |
| 11 | 2898848 |
| 12 | 13923468 |
| 13 | 75361600 |
| 14 | 450629592 |
| 15 | 2844358656 |
| 16 | 18224898790 |
| 17 | 116051632704 |
| 18 | 728724233988 |
| 19 | 4509502911328 |
| 20 | 27569637798116 |
| 21 | 167072272244352 |
| 22 | 1006431412676456 |
| 23 | 6037728817690112 |
| 24 | 36101656922629500 |