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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 0 |
| 4 | 3 |
| 5 | -10 |
| 6 | 21 |
| 7 | -25 |
| 8 | -23 |
| 9 | 228 |
| 10 | -737 |
| 11 | 1479 |
| 12 | -1245 |
| 13 | -4352 |
| 14 | 25206 |
| 15 | -72761 |
| 16 | 128245 |
| 17 | -38615 |
| 18 | -697798 |
| 19 | 3109043 |
| 20 | -8016819 |
| 21 | 11763729 |
| 22 | 6510069 |
| 23 | -108216128 |
| 24 | 403917707 |
| 25 | -925174519 |
| 26 | 1025709534 |
| 27 | 2228869018 |
| 28 | -16585014721 |
| 29 | 53758505915 |
| 30 | -107811969706 |
| 31 | 69758146717 |
| 32 | 478423936550 |
| 33 | -2520835801152 |
| 34 | 7208714823250 |