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 | -23 |
| 2 | 253 |
| 3 | -1794 |
| 4 | 9384 |
| 5 | -39491 |
| 6 | 142462 |
| 7 | -460483 |
| 8 | 1370041 |
| 9 | -3810479 |
| 10 | 10013533 |
| 11 | -25082512 |
| 12 | 60303171 |
| 13 | -139870107 |
| 14 | 314254704 |
| 15 | -686285914 |
| 16 | 1461009887 |
| 17 | -3039222369 |
| 18 | 6190256915 |
| 19 | -12366732828 |
| 20 | 24269855093 |