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 | -3 |
| 4 | 11 |
| 5 | -5 |
| 6 | 51 |
| 7 | 35 |
| 8 | 335 |
| 9 | 689 |
| 10 | 3055 |
| 11 | 9073 |
| 12 | 33891 |
| 13 | 114425 |
| 14 | 413623 |
| 15 | 1464661 |
| 16 | 5304803 |
| 17 | 19199859 |
| 18 | 70161499 |
| 19 | 257270227 |
| 20 | 948639463 |
| 21 | 3511150611 |
| 22 | 13047799395 |
| 23 | 48649126799 |
| 24 | 181968324231 |
| 25 | 682577156519 |
| 26 | 2567180111683 |
| 27 | 9678596662499 |
| 28 | 36571577629911 |