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 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 4 |
| 5 | 12 |
| 6 | 56 |
| 7 | 2 |
| 8 | 1360 |
| 9 | 2672 |
| 10 | 320 |
| 11 | 16 |
| 12 | 350000 |
| 13 | 431232 |
| 14 | 107904 |
| 15 | 12864 |
| 16 | 3872 |
| 17 | 320 |
| 18 | 255036992 |
| 19 | 234667968 |
| 20 | 98251776 |
| 21 | 19523136 |
| 22 | 10633728 |
| 23 | 1615552 |
| 24 | 1182720 |
| 25 | 163520 |
| 26 | 127360 |
| 27 | 13440 |