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Number of divisors of numbers containing in their decimal representation only the digits 0 and 1.
2

%I #12 Sep 19 2021 19:24:05

%S 1,4,2,9,2,8,4,16,8,8,4,18,4,16,4,25,4,32,8,18,16,16,2,32,8,16,12,36,

%T 4,16,4,36,4,16,16,72,8,32,8,32,8,64,4,36,16,8,2,50,8,32,8,36,4,48,4,

%U 64,4,16,4,36,4,16,32,49,4,16,4,36,4,64,4,128,4,32,16,72,4,32,4,50,4,32,6

%N Number of divisors of numbers containing in their decimal representation only the digits 0 and 1.

%H Harvey P. Dale, <a href="/A077809/b077809.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000005(A007088(n)).

%e a(6) = A000005(A007088(6)) = A000005(110) = 8, as 110 has divisors: 1, 2, 5, 10, 11, 22, 55 and 110.

%t With[{z1=Rest[FromDigits/@Tuples[{0,1},7]]},DivisorSigma[0,#]&/@z1] (* _Harvey P. Dale_, Sep 19 2021 *)

%o (PARI) a(n) = numdiv(fromdigits(binary(n),10)) \\ _David A. Corneth_, Sep 19 2021

%Y Cf. A000005, A007088, A077810.

%K nonn,easy,base

%O 1,2

%A _Reinhard Zumkeller_, Nov 16 2002