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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 20 |
| 7 | 330 |
| 8 | 5495 |
| 9 | 97405 |
| 10 | 1867446 |
| 11 | 38849790 |
| 12 | 875734035 |
| 13 | 21320230140 |
| 14 | 558453090910 |
| 15 | 15677076200786 |
| 16 | 469894617088260 |
| 17 | 14985440023696415 |
| 18 | 506831098757070010 |
| 19 | 18125347345533260190 |
| 20 | 683518670893880841921 |
| 21 | 27112243165544881804755 |
| 22 | 1128576366359460556636770 |