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 | 0 |
| 1 | 0 |
| 2 | 15228 |
| 3 | 705024 |
| 4 | 1885680 |
| 5 | -66355200 |
| 6 | -792382500 |
| 7 | -4986842112 |
| 8 | -22516232256 |
| 9 | -81696522240 |
| 10 | -252908835300 |
| 11 | -693126720000 |
| 12 | -1723987588752 |
| 13 | -3961019252736 |
| 14 | -8517765880260 |
| 15 | -17315965900800 |
| 16 | -33541737120000 |
| 17 | -62298041352192 |
| 18 | -111515651966916 |
| 19 | -193198552634880 |