A084561 - OEIS

A084561

Numbers with a square number of 1's in their binary expansion.

0, 1, 2, 4, 8, 15, 16, 23, 27, 29, 30, 32, 39, 43, 45, 46, 51, 53, 54, 57, 58, 60, 64, 71, 75, 77, 78, 83, 85, 86, 89, 90, 92, 99, 101, 102, 105, 106, 108, 113, 114, 116, 120, 128, 135, 139, 141, 142, 147, 149, 150, 153, 154, 156, 163, 165, 166, 169, 170, 172, 177, 178

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

Begins to differ from A084345 at the 22nd term.

There are A003099(n) terms with at most n bits, so a(n) is n sqrt log n times a bounded function of n (which does not tend toward a limit). - Charles R Greathouse IV, Mar 26 2013

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[0, 178], IntegerQ[Sqrt[Count[IntegerDigits[#, 2], 1]]]&] (* Jayanta Basu, May 24 2013 *)

PROG

(PARI) is(n)=issquare(hammingweight(n)) \\ Charles R Greathouse IV, Mar 26 2013

CROSSREFS

Cf. A001969, A000069, A052294, A084345.

Sequence in context: A019278 A267894 A084345 * A277166 A078613 A072202

Adjacent sequences: A084558 A084559 A084560 * A084562 A084563 A084564

KEYWORD

easy,nonn,base

AUTHOR

Jason Earls, Jun 27 2003

STATUS

approved