June 2018 Update

Task/Fractran/Julia/fractran.julia

@@ -0,0 +1,32 @@
+function fractran(n::Integer, ratios::Vector{<:Rational}, steplim::Integer)
+    rst = zeros(BigInt, steplim)
+    for i in 1:steplim
+        rst[i] = n
+        if (pos = findfirst(x -> isinteger(n * x), ratios)) > 0
+            n *= ratios[pos]
+        else
+            break
+        end
+    end
+    return rst
+end
+
+using IterTools
+macro ratio_str(s)
+    a = split(s, r"[\s,/]+")
+    return collect(parse(BigInt, n) // parse(BigInt, d) for (n, d) in partition(a, 2))
+end
+
+fracs = ratio"""17 / 91, 78 / 85, 19 / 51, 23 / 38, 29 / 33, 77 / 29, 95 / 23,
+                77 / 19, 1 / 17, 11 / 13, 13 / 11, 15 / 14, 15 / 2, 55 / 1"""
+println("The first 20 in the series are ", fractran(2, fracs, 20))
+
+prmfound = 0
+n = big(2)
+while prmfound < 20
+    if isinteger(log2(n))
+        prmfound += 1
+        println("Prime $prmfound found: $n is 2 ^ $(Int(log2(n)))")
+    end
+    n = fractran(n, fracs, 2)[2]
+end