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 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 88 |
| 5 | 670 |
| 6 | 6170 |
| 7 | 66360 |
| 8 | 815640 |
| 9 | 11272800 |
| 10 | 173132400 |
| 11 | 2925014400 |
| 12 | 53909394000 |
| 13 | 1076365290000 |
| 14 | 23144112591600 |
| 15 | 533193460800000 |
| 16 | 13102608591072000 |
| 17 | 342105146182800000 |
| 18 | 9457689380931792000 |
| 19 | 275988880808825184000 |
| 20 | 8477631163592791200000 |
| 21 | 273430368958004818560000 |
| 22 | 9238944655686318693120000 |