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 | -22 |
| 2 | 209 |
| 3 | -1122 |
| 4 | 3894 |
| 5 | -10956 |
| 6 | 35123 |
| 7 | -120362 |
| 8 | 337106 |
| 9 | -821854 |
| 10 | 2257728 |
| 11 | -6472050 |
| 12 | 15946777 |
| 13 | -37180990 |
| 14 | 95117858 |
| 15 | -239904786 |
| 16 | 552195127 |
| 17 | -1268645554 |
| 18 | 3023055717 |
| 19 | -7022547026 |
| 20 | 15717464257 |
| 21 | -35081020348 |