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 | -3 |
| 2 | -3 |
| 3 | 15 |
| 4 | -15 |
| 5 | 66 |
| 6 | -261 |
| 7 | 618 |
| 8 | -1155 |
| 9 | 1040 |
| 10 | 2361 |
| 11 | -11616 |
| 12 | 23733 |
| 13 | -27027 |
| 14 | 29394 |
| 15 | -132318 |
| 16 | 545790 |
| 17 | -1383459 |
| 18 | 2418896 |
| 19 | -3383679 |
| 20 | 4278462 |
| 21 | -3127320 |
| 22 | -8332866 |
| 23 | 42021990 |
| 24 | -99069516 |
| 25 | 160683318 |
| 26 | -200247795 |
| 27 | 214883010 |
| 28 | -345461022 |
| 29 | 1184850729 |
| 30 | -3966311448 |
| 31 | 9899287254 |
| 32 | -18787986009 |