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 | 0 |
| 2 | 0 |
| 3 | -2 |
| 4 | 4 |
| 5 | -6 |
| 6 | 12 |
| 7 | -26 |
| 8 | 52 |
| 9 | -102 |
| 10 | 204 |
| 11 | -410 |
| 12 | 820 |
| 13 | -1638 |
| 14 | 3276 |
| 15 | -6554 |
| 16 | 13108 |
| 17 | -26214 |
| 18 | 52428 |
| 19 | -104858 |
| 20 | 209716 |
| 21 | -419430 |
| 22 | 838860 |
| 23 | -1677722 |
| 24 | 3355444 |
| 25 | -6710886 |
| 26 | 13421772 |
| 27 | -26843546 |
| 28 | 53687092 |
| 29 | -107374182 |
| 30 | 214748364 |
| 31 | -429496730 |
| 32 | 858993460 |
| 33 | -1717986918 |
| 34 | 3435973836 |
| 35 | -6871947674 |