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 | 2 |
| 3 | 12 |
| 4 | 64 |
| 5 | 350 |
| 6 | 2024 |
| 7 | 12460 |
| 8 | 81638 |
| 9 | 567888 |
| 10 | 4180848 |
| 11 | 32470834 |
| 12 | 265219332 |
| 13 | 2271692124 |
| 14 | 20350705418 |
| 15 | 190216812260 |
| 16 | 1850993707960 |
| 17 | 18714559108142 |
| 18 | 196237054861920 |
| 19 | 2130518566431620 |
| 20 | 23912733627261670 |
| 21 | 277078872201375976 |
| 22 | 3310142647325149512 |