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) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 63 |
| 6 | 342 |
| 7 | 1998 |
| 8 | 11772 |
| 9 | 70308 |
| 10 | 420552 |
| 11 | 2521368 |
| 12 | 15120432 |
| 13 | 90710928 |
| 14 | 544218912 |
| 15 | 3265243488 |
| 16 | 19591180992 |
| 17 | 117546666048 |
| 18 | 705278316672 |
| 19 | 4231667380608 |
| 20 | 25389994205952 |
| 21 | 152339950119168 |
| 22 | 914039640248832 |
| 23 | 5484237750793728 |
| 24 | 32905426141965312 |
| 25 | 197432556307596288 |