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 | 2 |
| 2 | -17 |
| 3 | 104 |
| 4 | -560 |
| 5 | 2816 |
| 6 | -13568 |
| 7 | 63488 |
| 8 | -290816 |
| 9 | 1310720 |
| 10 | -5832704 |
| 11 | 25690112 |
| 12 | -112197632 |
| 13 | 486539264 |
| 14 | -2097152000 |
| 15 | 8992587776 |
| 16 | -38386270208 |
| 17 | 163208757248 |
| 18 | -691489734656 |
| 19 | 2920577761280 |
| 20 | -12300786335744 |
| 21 | 51677046505472 |
| 22 | -216603790671872 |
| 23 | 905997581287424 |