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 | -8 |
| 3 | 24 |
| 4 | 64 |
| 5 | -480 |
| 6 | -3968 |
| 7 | 34944 |
| 8 | 354304 |
| 9 | -4062720 |
| 10 | -51734528 |
| 11 | 724568064 |
| 12 | 11070521344 |
| 13 | -183240744960 |
| 14 | -3266330329088 |
| 15 | 62382319632384 |
| 16 | 1270842139869184 |
| 17 | -27507470234419200 |
| 18 | -630424777639067648 |
| 19 | 15250953398036987904 |
| 20 | 388362339077349965824 |