A173023 Number of numbers <= n having no isolated digits "11" in their binary representations.

1, 2, 3, 3, 4, 5, 5, 6, 7, 8, 9, 9, 9, 9, 10, 11, 12, 13, 14, 14, 15, 16, 16, 17, 17, 17, 17, 17, 18, 19, 20, 21, 22, 23, 24, 24, 25, 26, 26, 27, 28, 29, 30, 30, 30, 30, 31, 32, 32, 32, 32, 32, 32, 32, 32, 32, 33, 34, 35, 35, 36, 37, 38, 39, 40, 41, 42, 42, 43, 44, 44, 45, 46, 47

Offset

0,2

Comments

a(A173025(n+1)) = a(A173025(n)) + 1;

A173021(n) <= A173022(n) <= a(n).

Links

R. Zumkeller, Table of n, a(n) for n = 0..10000

Example

a(20) = #{0,1,2,4,5,7,8,9,10,14,15,16,17,18,20} = #{0,1,10,100,101,111,1000,1001,1010,1110,1111,10000,10001,10010,10100} = 15.

Mathematica

Accumulate[Table[If[Count[Split[IntegerDigits[n, 2]], {1, 1}]>0, 0, 1], {n, 0, 80}]] (* Harvey P. Dale, Feb 12 2017 *)

Crossrefs

Sequence in context: A049474 A076874 A127041 * A127039 A143091 A114539

Adjacent sequences: A173020 A173021 A173022 * A173024 A173025 A173026

Keyword

base,nonn

Author

Reinhard Zumkeller, Feb 07 2010

Status

approved