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 | 17 |
| 5 | 81 |
| 6 | 241 |
| 7 | 1 |
| 8 | 5601 |
| 9 | 62497 |
| 10 | 518561 |
| 11 | 313281 |
| 12 | 3999601 |
| 13 | -40669199 |
| 14 | 2177551377 |
| 15 | 7318933441 |
| 16 | 397613245121 |
| 17 | -1411251083199 |
| 18 | 9245424513601 |
| 19 | -1554110065897343 |
| 20 | 8222970963680721 |
| 21 | 2117868896399761 |
| 22 | 11780583339147607601 |
| 23 | -55331596875625839999 |