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 | -7 |
| 4 | 17 |
| 5 | -39 |
| 6 | 93 |
| 7 | -219 |
| 8 | 517 |
| 9 | -1219 |
| 10 | 2877 |
| 11 | -6787 |
| 12 | 16013 |
| 13 | -37779 |
| 14 | 89133 |
| 15 | -210291 |
| 16 | 496141 |
| 17 | -1170547 |
| 18 | 2761677 |
| 19 | -6515635 |
| 20 | 15372365 |
| 21 | -36268083 |
| 22 | 85567437 |
| 23 | -201879603 |
| 24 | 476295373 |
| 25 | -1123725619 |
| 26 | 2651210445 |
| 27 | -6255011635 |
| 28 | 14757474509 |
| 29 | -34817369907 |
| 30 | 82144763085 |
| 31 | -193804475187 |