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 | 1 |
| 4 | 3 |
| 5 | -4 |
| 6 | 1 |
| 7 | -15 |
| 8 | 25 |
| 9 | -4 |
| 10 | -7 |
| 11 | 1 |
| 12 | 105 |
| 13 | -210 |
| 14 | 70 |
| 15 | 60 |
| 16 | -15 |
| 17 | -11 |
| 18 | 1 |
| 19 | -945 |
| 20 | 2205 |
| 21 | -1120 |
| 22 | -630 |
| 23 | 70 |
| 24 | 350 |
| 25 | 126 |
| 26 | -15 |
| 27 | -26 |
| 28 | -16 |
| 29 | 1 |
| 30 | 10395 |
| 31 | -27720 |
| 32 | 18900 |
| 33 | 7875 |
| 34 | -2800 |
| 35 | -6930 |
| 36 | -1638 |
| 37 | 560 |
| 38 | 455 |
| 39 | 784 |
| 40 | 238 |
| 41 | -56 |
| 42 | -42 |
| 43 | -22 |
| 44 | 1 |
| 45 | -135135 |
| 46 | 405405 |
| 47 | -346500 |
| 48 | -114345 |
| 49 | 84700 |