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 | -2 |
| 2 | -1 |
| 3 | -2 |
| 4 | 9 |
| 5 | -2 |
| 6 | 10 |
| 7 | -16 |
| 8 | 38 |
| 9 | -98 |
| 10 | 53 |
| 11 | -116 |
| 12 | 340 |
| 13 | -434 |
| 14 | 463 |
| 15 | -990 |
| 16 | 2378 |
| 17 | -2792 |
| 18 | 3660 |
| 19 | -7058 |
| 20 | 11454 |
| 21 | -18900 |
| 22 | 24104 |
| 23 | -36206 |
| 24 | 81623 |
| 25 | -119400 |
| 26 | 128194 |
| 27 | -248062 |
| 28 | 447066 |
| 29 | -576154 |
| 30 | 880401 |
| 31 | -1415926 |
| 32 | 2297516 |
| 33 | -3724290 |
| 34 | 4854450 |
| 35 | -7299306 |
| 36 | 13411402 |
| 37 | -19129752 |
| 38 | 25135890 |
| 39 | -42841396 |
| 40 | 71321016 |