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 | -13 |
| 4 | 19 |
| 5 | -77 |
| 6 | 179 |
| 7 | -461 |
| 8 | 1075 |
| 9 | -3021 |
| 10 | 7219 |
| 11 | -17357 |
| 12 | 44083 |
| 13 | -103373 |
| 14 | 257075 |
| 15 | -627661 |
| 16 | 1469491 |
| 17 | -3511245 |
| 18 | 8547379 |
| 19 | -19764173 |
| 20 | 47344691 |
| 21 | -112038861 |
| 22 | 261254195 |
| 23 | -611161037 |
| 24 | 1435659315 |
| 25 | -3329070029 |
| 26 | 7743892531 |
| 27 | -18025911245 |
| 28 | 41566759987 |
| 29 | -95872193485 |