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 | 7 |
| 3 | 126 |
| 4 | 4276 |
| 5 | 234300 |
| 6 | 18877020 |
| 7 | 2100159600 |
| 8 | 308417610816 |
| 9 | 57786899446080 |
| 10 | 13452134426136000 |
| 11 | 3808606484711952000 |
| 12 | 1288711254432792833280 |
| 13 | 513583129024901529834240 |
| 14 | 238093035025913233419052800 |
| 15 | 127039392937347095305900800000 |
| 16 | 77298350216325487808699492352000 |