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 | 1 |
| 1 | 1 |
| 2 | 42 |
| 3 | 6006 |
| 4 | 1662804 |
| 5 | 701149020 |
| 6 | 396499770810 |
| 7 | 278607172289160 |
| 8 | 231471904322784840 |
| 9 | 219738059326729823880 |
| 10 | 232553551737813227594400 |
| 11 | 269396678720275351794712800 |
| 12 | 336839101096824285057473785200 |
| 13 | 449620757769949216266129125515200 |