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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 8 |
| 6 | 9862 |
| 7 | 1067638 |
| 8 | 55488142 |
| 9 | 3374967940 |
| 10 | 239187240144 |
| 11 | 15360134570696 |
| 12 | 964730606632516 |
| 13 | 61989683445413228 |
| 14 | 4005716717182224826 |
| 15 | 255967892553030600920 |
| 16 | 16378998506224697063588 |
| 17 | 1050504687249683771795632 |
| 18 | 67351449674771471216148786 |
| 19 | 4314151246752166099728445868 |