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 | 0 |
| 3 | 2 |
| 4 | -1 |
| 5 | 1 |
| 6 | -5 |
| 7 | 11 |
| 8 | -17 |
| 9 | 26 |
| 10 | -36 |
| 11 | 35 |
| 12 | -22 |
| 13 | 19 |
| 14 | -67 |
| 15 | 219 |
| 16 | -480 |
| 17 | 687 |
| 18 | -469 |
| 19 | -573 |
| 20 | 2508 |
| 21 | -4785 |
| 22 | 6370 |
| 23 | -6445 |
| 24 | 5235 |
| 25 | -4543 |
| 26 | 8681 |
| 27 | -26815 |
| 28 | 75043 |
| 29 | -173159 |
| 30 | 334721 |
| 31 | -563200 |
| 32 | 876876 |
| 33 | -1363232 |
| 34 | 2208921 |
| 35 | -3621971 |
| 36 | 5631540 |
| 37 | -7897299 |
| 38 | 9738858 |
| 39 | -10479294 |
| 40 | 9989646 |
| 41 | -9350820 |