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 | -32 |
| 2 | 275 |
| 3 | -1817 |
| 4 | 12134 |
| 5 | -87784 |
| 6 | 699894 |
| 7 | -6158058 |
| 8 | 59566464 |
| 9 | -630057696 |
| 10 | 7246806720 |
| 11 | -90151868160 |
| 12 | 1207028135520 |
| 13 | -17314992935040 |
| 14 | 265048030579680 |
| 15 | -4313510679824160 |
| 16 | 74387763047472000 |
| 17 | -1355291635314213120 |
| 18 | 26016022725597866880 |
| 19 | -524865277479851360640 |
| 20 | 11103724030717930095360 |