A080025 - OEIS

A080025

Numbers n having at least one divisor d such that in binary representation d and n/d have the same number of 1's as n.

1, 2, 4, 8, 9, 16, 18, 32, 36, 49, 64, 72, 98, 128, 133, 144, 196, 225, 256, 259, 266, 273, 288, 385, 392, 450, 512, 518, 532, 546, 576, 585, 645, 770, 784, 897, 900, 961, 1024, 1029, 1035, 1036, 1064, 1065, 1092, 1152, 1155, 1161, 1170, 1290, 1539, 1540, 1568

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OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

bn1Q[n_]:=AnyTrue[Union/@(Select[{DigitCount[#, 2, 1], DigitCount[n/#, 2, 1]}&/@ Divisors[n], #[[1]]==#[[2]]&]), #=={DigitCount[n, 2, 1]}&]; Select[Range[ 1600], bn1Q] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 03 2020 *)

CROSSREFS

Cf. A007088, A000120, A000005.

Cf. A080024(a(n))>0, A080026 is a subsequence.

Sequence in context: A330710 A023898 A125853 * A152111 A316856 A324524

Adjacent sequences: A080022 A080023 A080024 * A080026 A080027 A080028

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jan 21 2003

STATUS

approved