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 | -1 |
| 3 | 3 |
| 4 | -1 |
| 5 | -1 |
| 6 | 7 |
| 7 | -9 |
| 8 | 7 |
| 9 | 7 |
| 10 | -25 |
| 11 | 39 |
| 12 | -25 |
| 13 | -25 |
| 14 | 103 |
| 15 | -153 |
| 16 | 103 |
| 17 | 103 |
| 18 | -409 |
| 19 | 615 |
| 20 | -409 |
| 21 | -409 |
| 22 | 1639 |
| 23 | -2457 |
| 24 | 1639 |
| 25 | 1639 |
| 26 | -6553 |
| 27 | 9831 |
| 28 | -6553 |
| 29 | -6553 |
| 30 | 26215 |
| 31 | -39321 |
| 32 | 26215 |
| 33 | 26215 |
| 34 | -104857 |
| 35 | 157287 |
| 36 | -104857 |
| 37 | -104857 |
| 38 | 419431 |