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 | 0 |
| 3 | -1 |
| 4 | 0 |
| 5 | 4 |
| 6 | -3 |
| 7 | 0 |
| 8 | -16 |
| 9 | 60 |
| 10 | -45 |
| 11 | 0 |
| 12 | 64 |
| 13 | -1008 |
| 14 | 2520 |
| 15 | -1575 |
| 16 | 0 |
| 17 | -256 |
| 18 | 16320 |
| 19 | -105840 |
| 20 | 189000 |
| 21 | -99225 |
| 22 | 0 |
| 23 | 1024 |
| 24 | -261888 |
| 25 | 4055040 |
| 26 | -15800400 |
| 27 | 21829500 |
| 28 | -9823275 |
| 29 | 0 |
| 30 | -4096 |
| 31 | 4193280 |
| 32 | -149909760 |
| 33 | 1153152000 |
| 34 | -3178375200 |
| 35 | 3575672100 |
| 36 | -1404728325 |
| 37 | 0 |
| 38 | 16384 |
| 39 | -67104768 |
| 40 | 5459650560 |