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Smallest divisor of n that is also contained in the decimal representation of n.
4

%I #5 Mar 31 2016 11:44:04

%S 1,2,3,4,5,6,7,8,9,1,1,1,1,1,1,1,1,1,1,2,1,2,23,2,5,2,27,2,29,3,1,2,3,

%T 34,5,3,37,38,3,4,1,2,43,4,5,46,47,4,49,5,1,2,53,54,5,56,57,58,59,6,1,

%U 2,3,4,5,6,67,68,69,7,1,2,73,74,5,76,7,78,79,8,1,2,83,4,5,86,87,8,89,9,1

%N Smallest divisor of n that is also contained in the decimal representation of n.

%C 1 <= a(n) <= n;

%C a(A011531(n)) = 1; a(n) = n iff A121041(n) = 1.

%C a(n) = 1 for almost all n (measure 1). - _Charles R Greathouse IV_, Mar 31 2016

%e a(48) = Min{4, 8, 48} = 4;

%e a(49) = Min{49} = 49;

%e a(120) = Min{1, 2, 12, 20, 120} = 1;

%e a(121) = Min{1} = 1.

%o (PARI) substr(a,b)=a=digits(a);b=digits(b); for(i=0,#a-#b, for(j=1,#b, if(a[i+j]!=b[j], next(2))); return(1)); 0

%o a(n)=fordiv(n,d, if(substr(n,d), return(d))) \\ _Charles R Greathouse IV_, Mar 31 2016

%K nonn,base

%O 1,2

%A _Reinhard Zumkeller_, Jul 21 2006