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 | 0 |
| 3 | 1 |
| 4 | -2 |
| 5 | 3 |
| 6 | -4 |
| 7 | 7 |
| 8 | -18 |
| 9 | 51 |
| 10 | -136 |
| 11 | 339 |
| 12 | -814 |
| 13 | 1935 |
| 14 | -4620 |
| 15 | 11111 |
| 16 | -26842 |
| 17 | 64923 |
| 18 | -156944 |
| 19 | 379067 |
| 20 | -915078 |
| 21 | 2208711 |
| 22 | -5331476 |
| 23 | 12870639 |
| 24 | -31072754 |
| 25 | 75018195 |
| 26 | -181113240 |
| 27 | 437248771 |
| 28 | -1055610782 |
| 29 | 2548462143 |
| 30 | -6152518684 |
| 31 | 14853483127 |
| 32 | -35859484938 |
| 33 | 86572485771 |