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 | 0 |
| 4 | -1 |
| 5 | 0 |
| 6 | 5 |
| 7 | 0 |
| 8 | -45 |
| 9 | 0 |
| 10 | 665 |
| 11 | 0 |
| 12 | -14457 |
| 13 | 0 |
| 14 | 433741 |
| 15 | 0 |
| 16 | -17160421 |
| 17 | 0 |
| 18 | 865407905 |
| 19 | 0 |
| 20 | -54179057649 |
| 21 | 0 |
| 22 | 4122477869077 |
| 23 | 0 |
| 24 | -374673778941981 |
| 25 | 0 |
| 26 | 40087507726395689 |
| 27 | 0 |
| 28 | -4987405802167886825 |
| 29 | 0 |
| 30 | 713925031978621041757 |
| 31 | 0 |
| 32 | -116506260029721326349781 |
| 33 | 0 |
| 34 | 21501227314690679723073329 |