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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | -1 |
| 4 | 0 |
| 5 | 3 |
| 6 | -9 |
| 7 | 18 |
| 8 | -27 |
| 9 | 27 |
| 10 | 0 |
| 11 | -81 |
| 12 | 243 |
| 13 | -485 |
| 14 | 715 |
| 15 | -624 |
| 16 | -559 |
| 17 | 4550 |
| 18 | -14976 |
| 19 | 39286 |
| 20 | -92378 |
| 21 | 203034 |
| 22 | -424346 |
| 23 | 848692 |
| 24 | -1625754 |
| 25 | 2977832 |
| 26 | -5200299 |
| 27 | 8628633 |
| 28 | -13553462 |
| 29 | 20083622 |
| 30 | -28009215 |
| 31 | 36801609 |
| 32 | -45932172 |
| 33 | 55400904 |
| 34 | -64869636 |
| 35 | 64869636 |
| 36 | 0 |
| 37 | -349578528 |