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 | 0 |
| 1 | 1 |
| 2 | 18 |
| 3 | 361 |
| 4 | 7200 |
| 5 | 143641 |
| 6 | 2865618 |
| 7 | 57168721 |
| 8 | 1140508800 |
| 9 | 22753007281 |
| 10 | 453919636818 |
| 11 | 9055639729081 |
| 12 | 180658874944800 |
| 13 | 3604121859166921 |
| 14 | 71901778308393618 |
| 15 | 1434431444308705441 |
| 16 | 28616727107865715200 |