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) |
|---|---|
| 3 | 0 |
| 4 | 2 |
| 5 | 2 |
| 6 | 6 |
| 7 | -4 |
| 8 | 50 |
| 9 | -258 |
| 10 | 1862 |
| 11 | -14824 |
| 12 | 133506 |
| 13 | -1334950 |
| 14 | 14684582 |
| 15 | -176214828 |
| 16 | 2290792946 |
| 17 | -32071101034 |
| 18 | 481066515750 |
| 19 | -7697064251728 |
| 20 | 130850092279682 |
| 21 | -2355301661033934 |
| 22 | 44750731559645126 |
| 23 | -895014631192902100 |
| 24 | 18795307255050944562 |
| 25 | -413496759611120779858 |