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 | 0 |
| 3 | 1 |
| 4 | -2 |
| 5 | 4 |
| 6 | -9 |
| 7 | 21 |
| 8 | -48 |
| 9 | 105 |
| 10 | -218 |
| 11 | 429 |
| 12 | -803 |
| 13 | 1442 |
| 14 | -2521 |
| 15 | 4380 |
| 16 | -7734 |
| 17 | 14091 |
| 18 | -26468 |
| 19 | 50405 |
| 20 | -94980 |
| 21 | 172824 |
| 22 | -296704 |
| 23 | 467589 |
| 24 | -644459 |
| 25 | 678109 |
| 26 | -177123 |
| 27 | -1752141 |
| 28 | 7003180 |
| 29 | -19432494 |
| 30 | 46778567 |
| 31 | -104623822 |
| 32 | 224830880 |
| 33 | -473859273 |
| 34 | 992825436 |
| 35 | -2084921584 |