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 | -1 |
| 4 | 1 |
| 5 | 4 |
| 6 | -35 |
| 7 | 146 |
| 8 | -447 |
| 9 | 1133 |
| 10 | -2464 |
| 11 | 4355 |
| 12 | -4355 |
| 13 | -9296 |
| 14 | 77078 |
| 15 | -314636 |
| 16 | 1006145 |
| 17 | -2738565 |
| 18 | 6398155 |
| 19 | -12175809 |
| 20 | 14621376 |
| 21 | 14828330 |
| 22 | -179236815 |
| 23 | 786257460 |
| 24 | -2625667395 |
| 25 | 7412386254 |
| 26 | -17983703880 |
| 27 | 36057065030 |
| 28 | -49553122730 |
| 29 | -14585596720 |