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 | 119 |
| 6 | 708 |
| 7 | 4914 |
| 8 | 38976 |
| 9 | 347776 |
| 10 | 3447932 |
| 11 | 37601916 |
| 12 | 447352224 |
| 13 | 5765690544 |
| 14 | 80027220448 |
| 15 | 1190110692204 |
| 16 | 18878422622976 |
| 17 | 318180082610048 |
| 18 | 5678110761876224 |
| 19 | 106958628519952128 |
| 20 | 2120821833862388544 |
| 21 | 44155198873515034560 |
| 22 | 963081167548894179456 |