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 | -1 |
| 6 | 1 |
| 7 | -1 |
| 8 | 1 |
| 9 | -1 |
| 10 | 1 |
| 11 | -1 |
| 12 | 0 |
| 13 | 11 |
| 14 | -77 |
| 15 | 363 |
| 16 | -1364 |
| 17 | 4367 |
| 18 | -12375 |
| 19 | 31823 |
| 20 | -75581 |
| 21 | 167959 |
| 22 | -352715 |
| 23 | 705431 |
| 24 | -1352078 |
| 25 | 2496167 |
| 26 | -4457699 |
| 27 | 7728759 |
| 28 | -13055444 |
| 29 | 21572459 |
| 30 | -35072309 |
| 31 | 56663099 |
| 32 | -92561039 |
| 33 | 157073279 |
| 34 | -286097759 |
| 35 | 572195518 |
| 36 | -1251677664 |