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 | -3 |
| 5 | 1 |
| 6 | 3 |
| 7 | -6 |
| 8 | 1 |
| 9 | 15 |
| 10 | -10 |
| 11 | 1 |
| 12 | -15 |
| 13 | 45 |
| 14 | -15 |
| 15 | 1 |
| 16 | -105 |
| 17 | 105 |
| 18 | -21 |
| 19 | 1 |
| 20 | 105 |
| 21 | -420 |
| 22 | 210 |
| 23 | -28 |
| 24 | 1 |
| 25 | 945 |
| 26 | -1260 |
| 27 | 378 |
| 28 | -36 |
| 29 | 1 |
| 30 | -945 |
| 31 | 4725 |
| 32 | -3150 |
| 33 | 630 |
| 34 | -45 |
| 35 | 1 |
| 36 | -10395 |
| 37 | 17325 |
| 38 | -6930 |
| 39 | 990 |
| 40 | -55 |
| 41 | 1 |
| 42 | 10395 |
| 43 | -62370 |
| 44 | 51975 |
| 45 | -13860 |
| 46 | 1485 |
| 47 | -66 |
| 48 | 1 |
| 49 | 135135 |
| 50 | -270270 |
| 51 | 135135 |
| 52 | -25740 |
| 53 | 2145 |
| 54 | -78 |
| 55 | 1 |