OFFSET
1,10
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = 1 iff A121042(n) = n.
EXAMPLE
a(22) = #{2, 22} = 2;
a(23) = #{23} = 1;
a(24) = #{2, 4, 24} = 3.
MATHEMATICA
A121041[n_] := DivisorSum[n, 1 &, StringContainsQ[IntegerString[n], IntegerString[#]] &]; Array[A121041, 150] (* Paolo Xausa, Feb 25 2024 *)
PROG
(Haskell)
import Data.List (isInfixOf)
a121041 n = length $ filter (\d -> n `mod` d == 0
&& show d `isInfixOf` show n) [1..n]
-- Reinhard Zumkeller, Feb 11 2011
(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)=sumdiv(n, d, substr(n, d)) \\ Charles R Greathouse IV, Mar 31 2016
(Python)
from sympy import divisors
def a(n):
s = str(n)
return sum(1 for d in divisors(n, generator=True) if str(d) in s)
print([a(n) for n in range(1, 106)]) # Michael S. Branicky, Jul 11 2022
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Reinhard Zumkeller, Jul 21 2006
STATUS
approved