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 | 1 |
| 1 | 0 |
| 2 | -5 |
| 3 | 20 |
| 4 | -55 |
| 5 | 120 |
| 6 | -205 |
| 7 | 220 |
| 8 | 145 |
| 9 | -1680 |
| 10 | 5995 |
| 11 | -15580 |
| 12 | 32345 |
| 13 | -51480 |
| 14 | 44195 |
| 15 | 80620 |
| 16 | -543455 |
| 17 | 1770720 |
| 18 | -4365605 |
| 19 | 8608820 |
| 20 | -12607255 |
| 21 | 7384920 |
| 22 | 33496595 |
| 23 | -170910980 |
| 24 | 516160945 |
| 25 | -1210088880 |
| 26 | 2259550795 |
| 27 | -2987758780 |
| 28 | 653281145 |
| 29 | 12325669320 |