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 | 3 |
| 4 | -5 |
| 5 | 2 |
| 6 | 9 |
| 7 | -21 |
| 8 | 16 |
| 9 | 23 |
| 10 | -81 |
| 11 | 90 |
| 12 | 37 |
| 13 | -289 |
| 14 | 432 |
| 15 | -69 |
| 16 | -941 |
| 17 | 1874 |
| 18 | -1071 |
| 19 | -2685 |
| 20 | 7504 |
| 21 | -6961 |
| 22 | -5913 |
| 23 | 27882 |
| 24 | -35891 |
| 25 | -3817 |
| 26 | 95472 |
| 27 | -163437 |
| 28 | 60331 |
| 29 | 294050 |
| 30 | -681255 |
| 31 | 507867 |
| 32 | 761488 |
| 33 | -2631865 |
| 34 | 2886111 |
| 35 | 1268730 |
| 36 | -9418571 |
| 37 | 13922063 |
| 38 | -1966032 |
| 39 | -30793173 |
| 40 | 60603331 |
| 41 | -33742222 |
| 42 | -88447455 |