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 | 2 |
| 4 | 0 |
| 5 | -3 |
| 6 | 9 |
| 7 | 0 |
| 8 | 8 |
| 9 | -48 |
| 10 | 64 |
| 11 | 0 |
| 12 | -30 |
| 13 | 275 |
| 14 | -750 |
| 15 | 625 |
| 16 | 0 |
| 17 | 144 |
| 18 | -1800 |
| 19 | 7560 |
| 20 | -12960 |
| 21 | 7776 |
| 22 | 0 |
| 23 | -840 |
| 24 | 13426 |
| 25 | -77175 |
| 26 | 204085 |
| 27 | -252105 |
| 28 | 117649 |
| 29 | 0 |
| 30 | 5760 |
| 31 | -112896 |
| 32 | 831488 |
| 33 | -3010560 |
| 34 | 5734400 |
| 35 | -5505024 |
| 36 | 2097152 |
| 37 | 0 |
| 38 | -45360 |
| 39 | 1058508 |
| 40 | -9573228 |