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 | 0 |
| 1 | 3 |
| 2 | -2 |
| 3 | 15 |
| 4 | -18 |
| 5 | 76 |
| 6 | -126 |
| 7 | 405 |
| 8 | -802 |
| 9 | 2241 |
| 10 | -4884 |
| 11 | 12696 |
| 12 | -29100 |
| 13 | 72903 |
| 14 | -171490 |
| 15 | 421683 |
| 16 | -1005030 |
| 17 | 2448356 |
| 18 | -5873706 |
| 19 | 14243001 |
| 20 | -34280258 |
| 21 | 82936965 |
| 22 | -199930344 |
| 23 | 483172656 |
| 24 | -1165648152 |
| 25 | 2815517835 |
| 26 | -6794932418 |
| 27 | 16408304343 |
| 28 | -39606671610 |
| 29 | 95629756540 |