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 | 3 |
| 2 | 21 |
| 3 | 220 |
| 4 | 3060 |
| 5 | 53130 |
| 6 | 1107568 |
| 7 | 26978328 |
| 8 | 752538150 |
| 9 | 23667689815 |
| 10 | 828931106355 |
| 11 | 32006008361808 |
| 12 | 1350990969850340 |
| 13 | 61902409203193230 |
| 14 | 3060335715568296000 |
| 15 | 162392216278033616560 |
| 16 | 9206887338937200407418 |