34 lines
1.4 KiB
Text
34 lines
1.4 KiB
Text
using Primes
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function maxprimebases(ndig, maxbase)
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maxprimebases = [Int[]]
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nwithbases = ["0"]
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for tup in Iterators.product([0:maxbase-1 for _ in 1:ndig - 1]..., 1:maxbase-1)
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dig = collect(tup)
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foundbases = Int[]
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for b in maximum(dig)+1:maxbase
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if isprime(evalpoly(b, dig))
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push!(foundbases, b)
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end
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maxbase - b + length(foundbases) < length(maxprimebases) && break # shortcut if hopeless
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end
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if length(foundbases) > length(first(maxprimebases))
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maxprimebases = [foundbases]
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nwithbases = [prod(string.(reverse(dig), base = any(x -> x > 9, dig) ? 32 : 10))]
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elseif length(foundbases) == length(first(maxprimebases))
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push!(maxprimebases, foundbases)
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push!(nwithbases, prod(string.(reverse(dig), base = any(x -> x > 9, dig) ? 32 : 10)))
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end
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end
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alen, vlen = length(first(maxprimebases)), length(maxprimebases)
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println("\nThe maximum number of prime valued bases for base up to $maxbase numeric strings of length ",
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ndig, " is $alen. The value list of ", vlen > 1 ? "these" : "this", " is:")
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for i in eachindex(maxprimebases)
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println(nwithbases[i], maxprimebases[i][1] > 10 ? "(base 32)" : "", " => ", maxprimebases[i])
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end
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end
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for n in 1:5
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maxprimebases(n, 36)
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maxprimebases(n, 62)
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end
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