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 | 0 |
| 1 | -1 |
| 2 | 2 |
| 3 | -2 |
| 4 | 4 |
| 5 | -3 |
| 6 | 6 |
| 7 | -4 |
| 8 | 0 |
| 9 | -5 |
| 10 | 10 |
| 11 | -6 |
| 12 | 12 |
| 13 | -7 |
| 14 | 14 |
| 15 | -8 |
| 16 | 0 |
| 17 | -9 |
| 18 | 18 |
| 19 | -10 |
| 20 | 0 |
| 21 | -11 |
| 22 | 22 |
| 23 | -12 |
| 24 | 0 |
| 25 | -13 |
| 26 | 26 |
| 27 | -14 |
| 28 | 0 |
| 29 | -15 |
| 30 | 30 |
| 31 | -16 |
| 32 | 0 |
| 33 | -17 |
| 34 | 34 |
| 35 | -18 |
| 36 | 36 |
| 37 | -19 |
| 38 | 38 |
| 39 | -20 |
| 40 | 0 |
| 41 | -21 |
| 42 | 42 |
| 43 | -22 |
| 44 | 0 |
| 45 | -23 |
| 46 | 0 |
| 47 | -24 |
| 48 | 48 |
| 49 | -25 |
| 50 | 0 |
| 51 | -26 |
| 52 | 52 |
| 53 | -27 |
| 54 | 0 |
| 55 | -28 |
| 56 | 56 |
| 57 | -29 |
| 58 | 0 |
| 59 | -30 |
| 60 | 60 |
| 61 | -31 |
| 62 | 0 |
| 63 | -32 |
| 64 | 64 |
| 65 | -33 |
| 66 | 66 |
| 67 | -34 |
| 68 | 68 |
| 69 | -35 |
| 70 | 0 |
| 71 | -36 |
| 72 | 72 |
| 73 | -37 |