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 | 0 |
| 2 | 1 |
| 3 | -1 |
| 4 | 6 |
| 5 | 0 |
| 6 | -6 |
| 7 | 18 |
| 8 | 6 |
| 9 | -6 |
| 10 | -18 |
| 11 | 40 |
| 12 | 20 |
| 13 | 0 |
| 14 | -20 |
| 15 | -40 |
| 16 | 75 |
| 17 | 45 |
| 18 | 15 |
| 19 | -15 |
| 20 | -45 |
| 21 | -75 |
| 22 | 126 |
| 23 | 84 |
| 24 | 42 |
| 25 | 0 |
| 26 | -42 |
| 27 | -84 |
| 28 | -126 |
| 29 | 196 |
| 30 | 140 |
| 31 | 84 |
| 32 | 28 |
| 33 | -28 |
| 34 | -84 |
| 35 | -140 |
| 36 | -196 |
| 37 | 288 |
| 38 | 216 |
| 39 | 144 |
| 40 | 72 |
| 41 | 0 |
| 42 | -72 |
| 43 | -144 |
| 44 | -216 |
| 45 | -288 |
| 46 | 405 |
| 47 | 315 |
| 48 | 225 |
| 49 | 135 |
| 50 | 45 |
| 51 | -45 |
| 52 | -135 |
| 53 | -225 |
| 54 | -315 |
| 55 | -405 |
| 56 | 550 |
| 57 | 440 |
| 58 | 330 |
| 59 | 220 |
| 60 | 110 |
| 61 | 0 |
| 62 | -110 |
| 63 | -220 |
| 64 | -330 |
| 65 | -440 |
| 66 | -550 |
| 67 | 726 |
| 68 | 594 |
| 69 | 462 |
| 70 | 330 |
| 71 | 198 |
| 72 | 66 |
| 73 | -66 |