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 | -4 |
| 2 | 1 |
| 3 | 20 |
| 4 | -9 |
| 5 | 1 |
| 6 | -120 |
| 7 | 74 |
| 8 | -15 |
| 9 | 1 |
| 10 | 840 |
| 11 | -638 |
| 12 | 179 |
| 13 | -22 |
| 14 | 1 |
| 15 | -6720 |
| 16 | 5944 |
| 17 | -2070 |
| 18 | 355 |
| 19 | -30 |
| 20 | 1 |
| 21 | 60480 |
| 22 | -60216 |
| 23 | 24574 |
| 24 | -5265 |
| 25 | 625 |
| 26 | -39 |
| 27 | 1 |
| 28 | -604800 |
| 29 | 662640 |
| 30 | -305956 |
| 31 | 77224 |
| 32 | -11515 |
| 33 | 1015 |
| 34 | -49 |
| 35 | 1 |
| 36 | 6652800 |
| 37 | -7893840 |
| 38 | 4028156 |
| 39 | -1155420 |
| 40 | 203889 |