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 | -1 |
| 4 | 2 |
| 5 | -4 |
| 6 | 9 |
| 7 | -21 |
| 8 | 49 |
| 9 | -112 |
| 10 | 249 |
| 11 | -539 |
| 12 | 1143 |
| 13 | -2396 |
| 14 | 5013 |
| 15 | -10550 |
| 16 | 22420 |
| 17 | -48086 |
| 18 | 103703 |
| 19 | -223806 |
| 20 | 481388 |
| 21 | -1029507 |
| 22 | 2187944 |
| 23 | -4625058 |
| 24 | 9742223 |
| 25 | -20490753 |
| 26 | 43111808 |
| 27 | -90840465 |
| 28 | 191773014 |
| 29 | -405523635 |
| 30 | 858378825 |
| 31 | -1817304609 |
| 32 | 3845492204 |
| 33 | -8129023694 |
| 34 | 17162802918 |
| 35 | -36191083386 |