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 | -2 |
| 3 | 0 |
| 4 | -3 |
| 5 | 3 |
| 6 | 0 |
| 7 | -4 |
| 8 | 12 |
| 9 | 0 |
| 10 | 0 |
| 11 | -5 |
| 12 | 35 |
| 13 | 0 |
| 14 | -30 |
| 15 | 0 |
| 16 | -6 |
| 17 | 90 |
| 18 | 0 |
| 19 | -360 |
| 20 | 180 |
| 21 | 0 |
| 22 | -7 |
| 23 | 217 |
| 24 | 0 |
| 25 | -2730 |
| 26 | 3150 |
| 27 | -630 |
| 28 | 0 |
| 29 | -8 |
| 30 | 504 |
| 31 | 0 |
| 32 | -16800 |
| 33 | 33600 |
| 34 | -15120 |
| 35 | 0 |
| 36 | 0 |
| 37 | -9 |
| 38 | 1143 |
| 39 | 0 |
| 40 | -91854 |
| 41 | 283500 |
| 42 | -215460 |
| 43 | 0 |
| 44 | 22680 |
| 45 | 0 |
| 46 | -10 |
| 47 | 2550 |
| 48 | 0 |
| 49 | -466200 |
| 50 | 2085300 |
| 51 | -2381400 |
| 52 | 0 |
| 53 | 907200 |
| 54 | -226800 |