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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 0 |
| 5 | -1 |
| 6 | 36 |
| 7 | 0 |
| 8 | -17 |
| 9 | 4 |
| 10 | 576 |
| 11 | 0 |
| 12 | -380 |
| 13 | 148 |
| 14 | -15 |
| 15 | 14400 |
| 16 | 0 |
| 17 | -11804 |
| 18 | 5908 |
| 19 | -1015 |
| 20 | 56 |
| 21 | 518400 |
| 22 | 0 |
| 23 | -496944 |
| 24 | 290928 |
| 25 | -65120 |
| 26 | 6116 |
| 27 | -185 |
| 28 | 25401600 |
| 29 | 0 |
| 30 | -27460656 |
| 31 | 17936112 |
| 32 | -4733696 |
| 33 | 577556 |
| 34 | -28385 |
| 35 | 204 |
| 36 | 1625702400 |
| 37 | 0 |
| 38 | -1935293184 |
| 39 | 1371808128 |
| 40 | -405733232 |
| 41 | 57923264 |
| 42 | -3462648 |
| 43 | -6152 |
| 44 | 6209 |