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 | 2 |
| 3 | 1 |
| 4 | -6 |
| 5 | -9 |
| 6 | -1 |
| 7 | 24 |
| 8 | 72 |
| 9 | 24 |
| 10 | 1 |
| 11 | -120 |
| 12 | -600 |
| 13 | -400 |
| 14 | -50 |
| 15 | -1 |
| 16 | 720 |
| 17 | 5400 |
| 18 | 6000 |
| 19 | 1500 |
| 20 | 90 |
| 21 | 1 |
| 22 | -5040 |
| 23 | -52920 |
| 24 | -88200 |
| 25 | -36750 |
| 26 | -4410 |
| 27 | -147 |
| 28 | -1 |
| 29 | 40320 |
| 30 | 564480 |
| 31 | 1317120 |
| 32 | 823200 |
| 33 | 164640 |
| 34 | 10976 |
| 35 | 224 |
| 36 | 1 |
| 37 | -362880 |
| 38 | -6531840 |
| 39 | -20321280 |
| 40 | -17781120 |
| 41 | -5334336 |
| 42 | -592704 |
| 43 | -24192 |
| 44 | -324 |
| 45 | -1 |