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 | 4 |
| 3 | 36 |
| 4 | 288 |
| 5 | 7200 |
| 6 | 43200 |
| 7 | 2116800 |
| 8 | 33868800 |
| 9 | 914457600 |
| 10 | 9144576000 |
| 11 | 1106493696000 |
| 12 | 13277924352000 |
| 13 | 2243969215488000 |
| 14 | 31415569016832000 |
| 15 | 471233535252480000 |
| 16 | 15079473128079360000 |
| 17 | 4357967734014935040000 |
| 18 | 78443419212268830720000 |