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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 0 |
| 6 | 2 |
| 7 | 1 |
| 8 | -1 |
| 9 | 1 |
| 10 | 6 |
| 11 | 1 |
| 12 | -2 |
| 13 | 3 |
| 14 | -1 |
| 15 | 24 |
| 16 | 1 |
| 17 | -3 |
| 18 | 8 |
| 19 | -13 |
| 20 | 8 |
| 21 | 120 |
| 22 | 1 |
| 23 | -4 |
| 24 | 16 |
| 25 | -48 |
| 26 | 77 |
| 27 | -26 |
| 28 | 720 |
| 29 | 1 |
| 30 | -5 |
| 31 | 27 |
| 32 | -124 |
| 33 | 386 |
| 34 | -576 |
| 35 | 194 |
| 36 | 5040 |
| 37 | 1 |
| 38 | -6 |
| 39 | 41 |
| 40 | -259 |
| 41 | 1270 |
| 42 | -3905 |
| 43 | 5219 |
| 44 | -1142 |
| 45 | 40320 |
| 46 | 1 |
| 47 | -7 |
| 48 | 58 |
| 49 | -471 |
| 50 | 3244 |
| 51 | -16243 |
| 52 | 47701 |
| 53 | -55567 |
| 54 | 9736 |
| 55 | 362880 |