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 | -2 |
| 3 | 18 |
| 4 | -150 |
| 5 | 1234 |
| 6 | -10026 |
| 7 | 81078 |
| 8 | -653642 |
| 9 | 5259654 |
| 10 | -42268734 |
| 11 | 339383866 |
| 12 | -2723191254 |
| 13 | 21839901546 |
| 14 | -175088593334 |
| 15 | 1403249333706 |
| 16 | -11243655022134 |
| 17 | 90073138966378 |
| 18 | -721461395853162 |
| 19 | 5777933202466686 |
| 20 | -46268213346433298 |
| 21 | 370468327360598622 |
| 22 | -2966084621457856170 |
| 23 | 23745699326099825110 |