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 | 0 |
| 2 | 2 |
| 3 | 0 |
| 4 | 36 |
| 5 | -30 |
| 6 | 1384 |
| 7 | -1680 |
| 8 | 95120 |
| 9 | -269136 |
| 10 | 10673176 |
| 11 | -39346560 |
| 12 | 1646512480 |
| 13 | -9198926880 |
| 14 | 351447935136 |
| 15 | -2475812561040 |
| 16 | 99060435898112 |
| 17 | -904912972938240 |
| 18 | 34772619691749120 |
| 19 | -378998950170136320 |
| 20 | 14965802767502028672 |
| 21 | -197854178189523770880 |
| 22 | 7940955462403332290816 |