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A093640 Number of divisors of n whose binary representation is contained in that of n. 3
1, 2, 2, 3, 2, 4, 2, 4, 2, 4, 2, 6, 2, 4, 3, 5, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 3, 6, 2, 6, 2, 6, 2, 4, 2, 6, 2, 4, 3, 8, 2, 4, 2, 6, 4, 4, 2, 10, 2, 4, 3, 6, 2, 6, 4, 8, 3, 4, 2, 9, 2, 4, 4, 7, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 4, 6, 2, 6, 2, 10, 2, 4, 2, 6, 3, 4, 3, 8, 2, 8, 3, 6, 3, 4, 3, 12, 2, 4, 3, 6, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n)>1 for n>1; a(p) =2 for primes p.

a(A093641(n)) =A000005(A093641(n)), a(A093642(n)) < A000005(A093642(n)).

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Index entries for sequences related to binary expansion of n

EXAMPLE

n=18: divisors of 18: 1='1', 2='10', 3='11', 6='110', 9='1001' and 18='10010': four of them are binary substrings of '10010', therefore a(18) =4.

PROG

(Haskell)

import Data.List (isInfixOf)

a093640 n  = length [d | d <- [1..n], mod n d == 0,

                         show (a007088 d) `isInfixOf` show (a007088 n)]

-- Reinhard Zumkeller, Jan 22 2012

CROSSREFS

Cf. A078822, A007088.

Sequence in context: A043261 A157986 A025479 * A083903 A083867 A076888

Adjacent sequences:  A093637 A093638 A093639 * A093641 A093642 A093643

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Apr 07 2004

STATUS

approved

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Last modified October 16 16:39 EDT 2018. Contains 316266 sequences. (Running on oeis4.)