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) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 296 |
| 4 | 20958 |
| 5 | 2554344 |
| 6 | 474099840 |
| 7 | 124074010080 |
| 8 | 43429847756400 |
| 9 | 19565965561887360 |
| 10 | 11018376449767451520 |
| 11 | 7579467449864423769600 |
| 12 | 6251471405353507523097600 |
| 13 | 6087988343847192559805952000 |
| 14 | 6910412728595671664966422425600 |
| 15 | 9042510998634333921282477985689600 |