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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 12 |
| 5 | 204 |
| 6 | 5372 |
| 7 | 299592 |
| 8 | 33546240 |
| 9 | 7635496960 |
| 10 | 3518433853392 |
| 11 | 3275345183542176 |
| 12 | 6148914685509544960 |
| 13 | 23248573454127484128960 |
| 14 | 176848577040728399988915648 |
| 15 | 2704321280486889389857342715776 |
| 16 | 83076749736557240903566436660674560 |