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 | -9 |
| 3 | -45 |
| 4 | -231 |
| 5 | -1161 |
| 6 | -5643 |
| 7 | -26637 |
| 8 | -122895 |
| 9 | -557073 |
| 10 | -2490387 |
| 11 | -11010069 |
| 12 | -48234519 |
| 13 | -209715225 |
| 14 | -905969691 |
| 15 | -3892314141 |
| 16 | -16642998303 |
| 17 | -70866960417 |
| 18 | -300647710755 |
| 19 | -1271310319653 |
| 20 | -5360119185447 |
| 21 | -22539988369449 |
| 22 | -94557999988779 |
| 23 | -395824185999405 |