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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | -1 |
| 4 | -1 |
| 5 | 6 |
| 6 | -1 |
| 7 | -79 |
| 8 | 214 |
| 9 | 1378 |
| 10 | -11321 |
| 11 | -14855 |
| 12 | 611932 |
| 13 | -1739312 |
| 14 | -34374895 |
| 15 | 311453831 |
| 16 | 1548864398 |
| 17 | -42005057494 |
| 18 | 66254532775 |
| 19 | 5287751144127 |
| 20 | -45726542532086 |
| 21 | -568193240268798 |
| 22 | 12768316133375343 |
| 23 | 16933257518347115 |
| 24 | -3008868695961855284 |
| 25 | 21477836260078982762 |