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 | -31 |
| 2 | 403 |
| 3 | -2666 |
| 4 | 7254 |
| 5 | 17329 |
| 6 | -187488 |
| 7 | 384865 |
| 8 | 916050 |
| 9 | -4785594 |
| 10 | 267220 |
| 11 | 23607058 |
| 12 | 8499735 |
| 13 | -138349218 |
| 14 | -198872750 |
| 15 | 1055690151 |
| 16 | 1063384258 |
| 17 | -4561862102 |
| 18 | -6887455628 |
| 19 | 9053067640 |
| 20 | 53042071422 |