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 | 1 |
| 5 | -1 |
| 6 | 1 |
| 7 | -1 |
| 8 | 1 |
| 9 | -1 |
| 10 | 1 |
| 11 | -1 |
| 12 | 1 |
| 13 | -1 |
| 14 | 1 |
| 15 | -1 |
| 16 | 0 |
| 17 | 1 |
| 18 | -2 |
| 19 | 3 |
| 20 | -4 |
| 21 | 5 |
| 22 | -6 |
| 23 | 7 |
| 24 | -8 |
| 25 | 9 |
| 26 | -10 |
| 27 | 11 |
| 28 | -12 |
| 29 | 13 |
| 30 | -14 |
| 31 | 15 |
| 32 | -15 |
| 33 | 14 |
| 34 | -12 |
| 35 | 9 |
| 36 | -5 |
| 37 | 0 |
| 38 | 6 |
| 39 | -13 |
| 40 | 21 |
| 41 | -30 |
| 42 | 40 |
| 43 | -51 |
| 44 | 63 |
| 45 | -76 |
| 46 | 90 |
| 47 | -105 |
| 48 | 120 |
| 49 | -134 |
| 50 | 146 |
| 51 | -155 |
| 52 | 160 |
| 53 | -160 |
| 54 | 154 |
| 55 | -141 |
| 56 | 120 |
| 57 | -90 |
| 58 | 50 |
| 59 | 1 |
| 60 | -64 |
| 61 | 140 |
| 62 | -230 |
| 63 | 335 |
| 64 | -455 |
| 65 | 589 |
| 66 | -735 |
| 67 | 890 |
| 68 | -1050 |
| 69 | 1210 |
| 70 | -1364 |
| 71 | 1505 |