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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2667 |
| 5 | 0 |
| 6 | 1322832 |
| 7 | 28220416 |
| 8 | 64456564 |
| 9 | 28220416 |
| 10 | -10582656000 |
| 11 | -225791548416 |
| 12 | -3159513791196 |
| 13 | -112218399562752 |
| 14 | -1393939076116272 |
| 15 | -4364593638795264 |
| 16 | 43266457908132892 |
| 17 | 2086425405380843520 |
| 18 | 35001966103959783936 |
| 19 | 618735425426386200576 |
| 20 | 11874999923669881148220 |