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 | 0 |
| 2 | -3 |
| 3 | 0 |
| 4 | -3 |
| 5 | 0 |
| 6 | -3 |
| 7 | 9 |
| 8 | 0 |
| 9 | -3 |
| 10 | 9 |
| 11 | 0 |
| 12 | -3 |
| 13 | 18 |
| 14 | 0 |
| 15 | -3 |
| 16 | 18 |
| 17 | -27 |
| 18 | 0 |
| 19 | -3 |
| 20 | 27 |
| 21 | -27 |
| 22 | 0 |
| 23 | -3 |
| 24 | 27 |
| 25 | -54 |
| 26 | 0 |
| 27 | -3 |
| 28 | 36 |
| 29 | -81 |
| 30 | 0 |
| 31 | -3 |
| 32 | 36 |
| 33 | -108 |
| 34 | 81 |
| 35 | 0 |
| 36 | -3 |
| 37 | 45 |
| 38 | -135 |
| 39 | 81 |
| 40 | 0 |
| 41 | -3 |
| 42 | 45 |
| 43 | -189 |
| 44 | 162 |
| 45 | 0 |
| 46 | -3 |
| 47 | 54 |
| 48 | -216 |
| 49 | 243 |
| 50 | 0 |
| 51 | -3 |
| 52 | 54 |
| 53 | -270 |
| 54 | 405 |
| 55 | 0 |
| 56 | -3 |
| 57 | 63 |
| 58 | -324 |
| 59 | 486 |
| 60 | -243 |
| 61 | 0 |
| 62 | -3 |
| 63 | 63 |
| 64 | -378 |