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A086150
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Number of permutations of decimal digits of n which yield nonprime numbers.
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2
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1, 0, 0, 1, 0, 1, 0, 1, 1, 2, 0, 2, 0, 1, 2, 1, 0, 2, 1, 1, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 0, 1, 1, 1, 1, 2, 0, 1, 2, 2, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 0, 2, 0, 1, 2, 1, 1, 2, 0, 2, 2, 2, 1, 2, 2, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 0, 1, 1, 3, 1, 6, 3, 4, 6
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OFFSET
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1,10
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COMMENTS
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Leading zeros are allowed.
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LINKS
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FORMULA
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EXAMPLE
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n=117, digit-permutations={117,171,711} are all composites, so a(117)=3.
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MAPLE
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f:= proc(L) option remember;
nops(remove(isprime, map(t -> add(t[i]*10^(i-1), i=1..nops(t)), combinat:-permute(L))))
end proc:
seq(f(sort(convert(n, base, 10))), n=1..200); # Robert Israel, Aug 13 2017
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MATHEMATICA
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nd[x_, y_] := 10*x+y tn[x_] := Fold[nd, 0, x] Table[Count[Table[PrimeQ[tn[Part[Permutations[ IntegerDigits[w]], j]]], {j, 1, Length[Permutations[ IntegerDigits[w]]]}], False], {w, 1, 128}]
Table[Count[FromDigits/@Permutations[IntegerDigits[n]], _?(!PrimeQ[#]&)], {n, 110}] (* Harvey P. Dale, Dec 24 2016 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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