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 | 0 |
| 1 | 1 |
| 2 | 66 |
| 3 | 924 |
| 4 | 7400 |
| 5 | 44040 |
| 6 | 217392 |
| 7 | 942592 |
| 8 | 3714048 |
| 9 | 13593600 |
| 10 | 46914560 |
| 11 | 154328064 |
| 12 | 487778304 |
| 13 | 1490384896 |
| 14 | 4423372800 |
| 15 | 12801146880 |
| 16 | 36235378688 |
| 17 | 100580917248 |
| 18 | 274361352192 |
| 19 | 736775372800 |
| 20 | 1950815354880 |
| 21 | 5099601002496 |
| 22 | 13176144920576 |
| 23 | 33682341494784 |