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 | 0 |
| 2 | 1 |
| 3 | -1 |
| 4 | 1 |
| 5 | -1 |
| 6 | 1 |
| 7 | -1 |
| 8 | 0 |
| 9 | 7 |
| 10 | -35 |
| 11 | 119 |
| 12 | -329 |
| 13 | 791 |
| 14 | -1715 |
| 15 | 3430 |
| 16 | -6419 |
| 17 | 11319 |
| 18 | -18767 |
| 19 | 28763 |
| 20 | -38759 |
| 21 | 38759 |
| 22 | 1 |
| 23 | -149228 |
| 24 | 572057 |
| 25 | -1615429 |
| 26 | 3979001 |
| 27 | -9014851 |
| 28 | 19251001 |
| 29 | -39309301 |
| 30 | 77558760 |
| 31 | -149239771 |
| 32 | 282712561 |
| 33 | -532577025 |
| 34 | 1008032953 |
| 35 | -1934671809 |
| 36 | 3787949521 |