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 A077809 Number of divisors of numbers containing in their decimal representation only the digits 0 and 1. 2
 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, 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, 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 FORMULA a(n) = A000005(A007088(n)). EXAMPLE a(6) = A000005(A007088(6)) = A000005(110) = 8, as 110 has divisors: 1, 2, 5, 10, 11, 22, 55 and 110. MATHEMATICA With[{z1=Rest[FromDigits/@Tuples[{0, 1}, 7]]}, DivisorSigma[0, #]&/@z1] (* Harvey P. Dale, Sep 19 2021 *) PROG (PARI) a(n) = numdiv(fromdigits(binary(n), 10)) \\ David A. Corneth, Sep 19 2021 CROSSREFS Cf. A000005, A007088, A077810. Sequence in context: A115881 A180434 A201574 * A201281 A095303 A060734 Adjacent sequences: A077806 A077807 A077808 * A077810 A077811 A077812 KEYWORD nonn,easy,base AUTHOR Reinhard Zumkeller, Nov 16 2002 STATUS approved

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Last modified August 15 00:19 EDT 2024. Contains 375171 sequences. (Running on oeis4.)