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 | 9 |
| 4 | -11 |
| 5 | 41 |
| 6 | -87 |
| 7 | 241 |
| 8 | -367 |
| 9 | 1185 |
| 10 | -2207 |
| 11 | 5441 |
| 12 | -10431 |
| 13 | 24961 |
| 14 | -46207 |
| 15 | 124161 |
| 16 | -218879 |
| 17 | 503297 |
| 18 | -1028607 |
| 19 | 2319361 |
| 20 | -4275199 |
| 21 | 10434561 |
| 22 | -19826687 |
| 23 | 43847681 |
| 24 | -85651455 |
| 25 | 191225857 |
| 26 | -365699071 |
| 27 | 849625089 |
| 28 | -1588051967 |
| 29 | 3444539393 |
| 30 | -7070580735 |
| 31 | 15214903297 |