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 | -1 |
| 3 | -1 |
| 4 | 7 |
| 5 | 1 |
| 6 | -38 |
| 7 | -5 |
| 8 | 11 |
| 9 | 7 |
| 10 | -3263 |
| 11 | -15 |
| 12 | 13399637 |
| 13 | 7601 |
| 14 | -8364 |
| 15 | -91 |
| 16 | 1437423473 |
| 17 | 3617 |
| 18 | -177451280177 |
| 19 | -745739 |
| 20 | 166416763419 |
| 21 | 3317609 |
| 22 | -17730427802974 |
| 23 | -5981591 |
| 24 | 51257173898346323 |
| 25 | 5436374093 |
| 26 | -107154672791057 |
| 27 | -213827575 |