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 | 1 |
| 2 | -9 |
| 3 | -19 |
| 4 | 71 |
| 5 | 261 |
| 6 | -449 |
| 7 | -3059 |
| 8 | 1431 |
| 9 | 32021 |
| 10 | 17711 |
| 11 | -302499 |
| 12 | -479609 |
| 13 | 2545381 |
| 14 | 7341471 |
| 15 | -18112339 |
| 16 | -91527049 |
| 17 | 89596341 |
| 18 | 1004866831 |
| 19 | 108903421 |
| 20 | -9939764889 |
| 21 | -11028799099 |
| 22 | 88368849791 |
| 23 | 198656840781 |
| 24 | -685031657129 |
| 25 | -2671600064939 |