A004764 Numbers whose binary expansion does not begin 110.

0, 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86

Offset

1,3

Links

Table of n, a(n) for n=1..72.

Formula

a(n) = n - 1, 1 <= n <= 6, a(2^(m+2) + 2^m + k + 2) = 2^(m+2) + 2^(m+1) + 2^m + k, m >= 0, 0 <= k < (2^(m+2) + 2^m). - Yosu Yurramendi, Aug 08 2016

Mathematica

Flatten[Insert[Select[Range[120], If[Length[IntegerDigits[ #, 2]] >= 3, Not[IntegerDigits[ #, 2][[1]] == 1 && IntegerDigits[ #, 2][[2]] == 1 && IntegerDigits[ #, 2][[3]] == 0 ]] &], {0, 1, 2, 3}, 1]] (* Stefan Steinerberger, Apr 15 2006 *)
Join[{0, 1, 2, 3}, Select[Range[4, 90], Take[IntegerDigits[#, 2], 3]!={1, 1, 0}&]] (* Harvey P. Dale, Feb 27 2012 *)

Crossrefs

Cf. A007088.

Sequence in context: A360009 A359905 A316465 * A128649 A032894 A032853

Adjacent sequences: A004761 A004762 A004763 * A004765 A004766 A004767

Keyword

nonn,easy,base

Author

N. J. A. Sloane

Status

approved