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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 0 |
| 5 | 24 |
| 6 | -8 |
| 7 | 104 |
| 8 | -48 |
| 9 | 352 |
| 10 | 80 |
| 11 | 1424 |
| 12 | -2480 |
| 13 | 8736 |
| 14 | 2048 |
| 15 | 16384 |
| 16 | -7008 |
| 17 | 111456 |
| 18 | -80384 |
| 19 | 473600 |
| 20 | -427008 |
| 21 | 1630976 |
| 22 | 750592 |
| 23 | 5731232 |
| 24 | -12709664 |
| 25 | 36894720 |
| 26 | 12300416 |
| 27 | 68246368 |
| 28 | -38345568 |
| 29 | 459223232 |
| 30 | -401666240 |
| 31 | 2015330304 |
| 32 | -862152384 |
| 33 | 5535523520 |
| 34 | 4631692288 |
| 35 | 21015756800 |
| 36 | -61319782400 |
| 37 | 165674113600 |
| 38 | 46426506688 |
| 39 | 279934140416 |
| 40 | -484569911296 |