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 | -3 |
| 3 | 13 |
| 4 | -87 |
| 5 | 841 |
| 6 | -10683 |
| 7 | 167413 |
| 8 | -3113967 |
| 9 | 66991441 |
| 10 | -1635760563 |
| 11 | 44683635613 |
| 12 | -1350018280647 |
| 13 | 44694643670041 |
| 14 | -1608962582321643 |
| 15 | 62572776778020613 |
| 16 | -2614314267900284127 |
| 17 | 116781203402752052641 |
| 18 | -5553985490569476301923 |