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) |
|---|---|
| 4 | 1 |
| 5 | -2 |
| 6 | 0 |
| 7 | 4 |
| 8 | -24 |
| 9 | 36 |
| 10 | 0 |
| 11 | -64 |
| 12 | 252 |
| 13 | -290 |
| 14 | 0 |
| 15 | 396 |
| 16 | -1472 |
| 17 | 1380 |
| 18 | 0 |
| 19 | -944 |
| 20 | 4830 |
| 21 | -4248 |
| 22 | 0 |
| 23 | -1268 |
| 24 | -6048 |
| 25 | 8040 |
| 26 | 0 |
| 27 | 12528 |
| 28 | -16744 |
| 29 | -3706 |
| 30 | 0 |
| 31 | -20976 |
| 32 | 84480 |
| 33 | -31284 |
| 34 | 0 |
| 35 | -31312 |
| 36 | -113643 |
| 37 | 101542 |
| 38 | 0 |
| 39 | 152892 |
| 40 | -115920 |
| 41 | -104792 |
| 42 | 0 |
| 43 | -96576 |
| 44 | 534612 |
| 45 | -112914 |
| 46 | 0 |
| 47 | -369544 |
| 48 | -370944 |
| 49 | 334864 |
| 50 | 0 |
| 51 | 603936 |
| 52 | -577738 |
| 53 | -22554 |
| 54 | 0 |