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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 32256 |
| 9 | 169632 |
| 10 | 737364 |
| 11 | 2731444 |
| 12 | 8875868 |
| 13 | 25894376 |
| 14 | 69053375 |
| 15 | 170694383 |
| 16 | 395443223 |
| 17 | 866147111 |
| 18 | 1806459866 |
| 19 | 3608498678 |
| 20 | 6937282452 |
| 21 | 12887902732 |
| 22 | 23216767894 |
| 23 | 40675018726 |
| 24 | 69480583966 |
| 25 | 115975600846 |
| 26 | 189528370396 |
| 27 | 303753983092 |