OFFSET
1,10
COMMENTS
From Robert Israel, Aug 13 2017: (Start)
Leading zeros are allowed.
a(n) = 0 for n in A003459. (End)
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
n=117, digit-permutations={117,171,711} are all composites, so a(117)=3.
MAPLE
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
MATHEMATICA
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 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Labos Elemer, Aug 04 2003
STATUS
approved