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 | 3 |
| 2 | 0 |
| 3 | 15 |
| 4 | 0 |
| 5 | -1 |
| 6 | 105 |
| 7 | 0 |
| 8 | -10 |
| 9 | 0 |
| 10 | 945 |
| 11 | 0 |
| 12 | -105 |
| 13 | 0 |
| 14 | 1 |
| 15 | 10395 |
| 16 | 0 |
| 17 | -1260 |
| 18 | 0 |
| 19 | 21 |
| 20 | 0 |
| 21 | 135135 |
| 22 | 0 |
| 23 | -17325 |
| 24 | 0 |
| 25 | 378 |
| 26 | 0 |
| 27 | -1 |
| 28 | 2027025 |
| 29 | 0 |
| 30 | -270270 |
| 31 | 0 |
| 32 | 6930 |
| 33 | 0 |
| 34 | -36 |
| 35 | 0 |
| 36 | 34459425 |
| 37 | 0 |
| 38 | -4729725 |
| 39 | 0 |
| 40 | 135135 |
| 41 | 0 |
| 42 | -990 |
| 43 | 0 |
| 44 | 1 |
| 45 | 654729075 |
| 46 | 0 |
| 47 | -91891800 |
| 48 | 0 |
| 49 | 2837835 |
| 50 | 0 |
| 51 | -25740 |
| 52 | 0 |
| 53 | 55 |
| 54 | 0 |
| 55 | 13749310575 |
| 56 | 0 |
| 57 | -1964187225 |
| 58 | 0 |
| 59 | 64324260 |
| 60 | 0 |
| 61 | -675675 |
| 62 | 0 |
| 63 | 2145 |
| 64 | 0 |
| 65 | -1 |