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 | 1 |
| 2 | -3 |
| 3 | 8 |
| 4 | -32 |
| 5 | 149 |
| 6 | -831 |
| 7 | 5340 |
| 8 | -38744 |
| 9 | 316161 |
| 10 | -2846611 |
| 11 | 28263960 |
| 12 | -305651048 |
| 13 | 3593550245 |
| 14 | -45584631743 |
| 15 | 622159233948 |
| 16 | -9091059243792 |
| 17 | 141783419182561 |
| 18 | -2351573180823939 |
| 19 | 41355560621409352 |
| 20 | -768924714448510480 |