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 | -1 |
| 3 | 5 |
| 4 | 1 |
| 5 | -41 |
| 6 | 31 |
| 7 | 461 |
| 8 | -895 |
| 9 | -6481 |
| 10 | 22591 |
| 11 | 107029 |
| 12 | -604031 |
| 13 | -1964665 |
| 14 | 17669471 |
| 15 | 37341149 |
| 16 | -567425279 |
| 17 | -627491489 |
| 18 | 19919950975 |
| 19 | 2669742629 |
| 20 | -759627879679 |
| 21 | 652838174519 |
| 22 | 31251532771999 |
| 23 | -59976412450835 |
| 24 | -1377594095061119 |
| 25 | 4256461892701199 |
| 26 | 64623242860354751 |