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 | 0 |
| 2 | -1 |
| 3 | 0 |
| 4 | 3 |
| 5 | 0 |
| 6 | -5 |
| 7 | 0 |
| 8 | 7 |
| 9 | 0 |
| 10 | -45 |
| 11 | 0 |
| 12 | 7601 |
| 13 | 0 |
| 14 | -91 |
| 15 | 0 |
| 16 | 54255 |
| 17 | 0 |
| 18 | -745739 |
| 19 | 0 |
| 20 | 3317609 |
| 21 | 0 |
| 22 | -17944773 |
| 23 | 0 |
| 24 | 5436374093 |
| 25 | 0 |
| 26 | -213827575 |
| 27 | 0 |
| 28 | 641235447783 |
| 29 | 0 |
| 30 | -249859397004145 |
| 31 | 0 |
| 32 | 238988952277727 |
| 33 | 0 |
| 34 | -85063699326111 |
| 35 | 0 |
| 36 | 921034504356871708055 |
| 37 | 0 |
| 38 | -108409774812137683 |