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 | -1 |
| 2 | 0 |
| 3 | 3 |
| 4 | -4 |
| 5 | -25 |
| 6 | 114 |
| 7 | 287 |
| 8 | -4152 |
| 9 | 1647 |
| 10 | 192230 |
| 11 | -807961 |
| 12 | -10164804 |
| 13 | 111209111 |
| 14 | 454840554 |
| 15 | -14657978385 |
| 16 | 21202175504 |
| 17 | 1988791958879 |
| 18 | -15488971798194 |
| 19 | -260886468394153 |
| 20 | 4872247004699460 |
| 21 | 23537372210149959 |
| 22 | -1365745577227898350 |
| 23 | 4274609859520565663 |
| 24 | 364461939727273277016 |