A121042 Smallest divisor of n that is also contained in the decimal representation of n.

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, 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, 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

Offset

1,2

Comments

1 <= a(n) <= n;

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

a(n) = 1 for almost all n (measure 1). - Charles R Greathouse IV, Mar 31 2016

Links

Table of n, a(n) for n=1..91.

Example

a(48) = Min{4, 8, 48} = 4;
a(49) = Min{49} = 49;
a(120) = Min{1, 2, 12, 20, 120} = 1;
a(121) = Min{1} = 1.

Prog

(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
a(n)=fordiv(n, d, if(substr(n, d), return(d))) \\ Charles R Greathouse IV, Mar 31 2016

Crossrefs

Sequence in context: A256229 A052423 A126616 * A369529 A000030 A179635

Adjacent sequences: A121039 A121040 A121041 * A121043 A121044 A121045

Keyword

nonn,base

Author

Reinhard Zumkeller, Jul 21 2006

Status

approved