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 | 0 |
| 3 | 6 |
| 4 | 48 |
| 5 | 1020 |
| 6 | 32232 |
| 7 | 2097144 |
| 8 | 268369920 |
| 9 | 68719472640 |
| 10 | 35184338533920 |
| 11 | 36028797018963936 |
| 12 | 73786976226114539520 |
| 13 | 302231454903657293676480 |
| 14 | 2475880078570197599844819072 |
| 15 | 40564819207303340847860140736640 |
| 16 | 1329227995784915854457062986570792960 |