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A143264 A positive integer n is included if the binary representation of the number of divisors of n does not occur anywhere in the binary representation of n. 2
3, 4, 6, 7, 9, 10, 14, 15, 16, 18, 20, 21, 22, 26, 27, 30, 31, 32, 42, 46, 48, 54, 55, 58, 62, 63, 64, 68, 72, 75, 78, 84, 85, 86, 87, 90, 91, 93, 94, 95, 102, 105, 106, 110, 111, 112, 114, 118, 119, 120, 122, 123, 125, 126, 127, 132, 144, 147, 148, 150, 154, 160, 164 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..63.

EXAMPLE

30 has 8 divisors. 30 in binary is 11110. 8 in binary is 1000. The string 1000 does not occur anywhere in the string 11110. So 30 occurs in this sequence.

MATHEMATICA

bndQ[n_]:=Module[{bn=IntegerDigits[n, 2], dn=IntegerDigits[ DivisorSigma[ 0, n], 2]}, !MemberQ[ Partition[ bn, Length[dn], 1], dn]]; Select[Range[ 200], bndQ] (* Harvey P. Dale, Nov 01 2013 *)

CROSSREFS

Cf. A143262, A143263.

Sequence in context: A068675 A190858 A026315 * A126332 A039026 A123540

Adjacent sequences:  A143261 A143262 A143263 * A143265 A143266 A143267

KEYWORD

base,nonn

AUTHOR

Leroy Quet, Aug 03 2008

EXTENSIONS

Extended by Ray Chandler, Nov 09 2008

STATUS

approved

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Last modified November 20 06:06 EST 2018. Contains 317385 sequences. (Running on oeis4.)