A143071 A positive integer n is included if the number of 1's in the binary representation of n is a power of 2 (including being possibly 1).

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 17, 18, 20, 23, 24, 27, 29, 30, 32, 33, 34, 36, 39, 40, 43, 45, 46, 48, 51, 53, 54, 57, 58, 60, 64, 65, 66, 68, 71, 72, 75, 77, 78, 80, 83, 85, 86, 89, 90, 92, 96, 99, 101, 102, 105, 106, 108, 113, 114, 116, 120, 128, 129, 130, 132, 135

Offset

1,2

Links

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

Formula

A209229(A000120(a(n))) = 1. - Reinhard Zumkeller, Sep 14 2014

Example

34 in binary is 100010. This has 2 ones. And since 2 is a power of 2, 34 is included in the sequence.

Maple

a:=proc(n) local nn, n1: nn:=convert(n, base, 2): n1:=add(nn[j], j=1..nops(nn)): if 0 < n1 and type(log[2](n1), integer)=true then n else end if end proc: seq(a(n), n=1..140); # Emeric Deutsch, Aug 13 2008

Mathematica

Select[Range[150], IntegerQ[Log2[DigitCount[#, 2, 1]]]&] (* Harvey P. Dale, Sep 26 2020 *)

Prog

(Haskell)
a143071 n = a143071_list !! (n-1)
a143071_list = filter ((== 1) . a209229 . a000120) [1..]
-- Reinhard Zumkeller, Sep 14 2014

Crossrefs

Cf. A000120, A143070, A143072, A209229.

For complement see A271499.

Sequence in context: A082415 A005236 A051250 * A305759 A143513 A062849

Adjacent sequences: A143068 A143069 A143070 * A143072 A143073 A143074

Keyword

base,nonn

Author

Leroy Quet, Jul 22 2008

Extensions

More terms from Emeric Deutsch, Aug 13 2008

Status

approved