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 | -1 |
| 5 | 8 |
| 6 | 1 |
| 7 | 21 |
| 8 | 0 |
| 9 | 55 |
| 10 | -1 |
| 11 | 144 |
| 12 | 1 |
| 13 | 377 |
| 14 | 0 |
| 15 | 987 |
| 16 | -1 |
| 17 | 2584 |
| 18 | 1 |
| 19 | 6765 |
| 20 | 0 |
| 21 | 17711 |
| 22 | -1 |
| 23 | 46368 |
| 24 | 1 |
| 25 | 121393 |
| 26 | 0 |
| 27 | 317811 |
| 28 | -1 |
| 29 | 832040 |
| 30 | 1 |
| 31 | 2178309 |
| 32 | 0 |
| 33 | 5702887 |
| 34 | -1 |
| 35 | 14930352 |
| 36 | 1 |
| 37 | 39088169 |
| 38 | 0 |
| 39 | 102334155 |
| 40 | -1 |
| 41 | 267914296 |
| 42 | 1 |
| 43 | 701408733 |
| 44 | 0 |
| 45 | 1836311903 |
| 46 | -1 |
| 47 | 4807526976 |
| 48 | 1 |