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A173023 Number of numbers <= n having no isolated digits "11" in their binary representations. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 23 12:45 EDT 2017. Contains 286915 sequences.