A179857 - OEIS

A179857

Smallest number greater than n having in binary representation exactly twice the number of ones as n has in binary representation.

3, 3, 15, 5, 15, 15, 63, 9, 15, 15, 63, 15, 63, 63, 255, 17, 23, 23, 63, 23, 63, 63, 255, 27, 63, 63, 255, 63, 255, 255, 1023, 33, 39, 39, 63, 39, 63, 63, 255, 43, 63, 63, 255, 63, 255, 255, 1023, 51, 63, 63, 255, 63, 255, 255, 1023, 63, 255, 255, 1023, 255, 1023, 1023

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OFFSET

1,1

COMMENTS

a(n) = Min{m: m > n and A000120(m) = 2*A000120(n)};

a(n) is odd;

n < a(n) < A000290(A062383(n));

a(A000079(n)) = A000051(n);

A024036 and A000225 give record values and where they occur.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Index entries for sequences related to binary expansion of n

MATHEMATICA

br2[n_]:=Module[{k=If[EvenQ[n], n+1, n+2], t=2*DigitCount[n, 2, 1]}, While[ DigitCount[ k, 2, 1]!=t, k=k+2]; k]; Array[br2, 70] (* Harvey P. Dale, Sep 20 2016 *)

PROG

(PARI) a(n) = my(k=n+1, h=hammingweight(n)); while (hammingweight(k) != 2*h, k++); k; \\ Michel Marcus, Nov 13 2023

CROSSREFS

Cf. A000120, A086799.

Cf. A000290, A062383.

Cf. A000051, A000079.

Cf. A000225, A024036.

Sequence in context: A287188 A100347 A165405 * A260078 A163590 A344850

Adjacent sequences: A179854 A179855 A179856 * A179858 A179859 A179860

KEYWORD

base,nonn

AUTHOR

Reinhard Zumkeller, Jul 31 2010

EXTENSIONS

Definition clarified by Harvey P. Dale, Sep 20 2016

STATUS

approved