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A033015 Numbers n such that every run of digits of n in base 2 has length >=2. 20
3, 7, 12, 15, 24, 28, 31, 48, 51, 56, 60, 63, 96, 99, 103, 112, 115, 120, 124, 127, 192, 195, 199, 204, 207, 224, 227, 231, 240, 243, 248, 252, 255, 384, 387, 391, 396, 399, 408, 412, 415, 448, 451, 455, 460, 463, 480, 483, 487, 496, 499, 504, 508, 511, 768 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

See A033016 and following for the variants in other bases, A043291 for run lengths equal to 2 (which has a very simple formula) and A033001 and following for the analog of the latter in other bases. - M. F. Hasler, Feb 01 2014

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[2000], Min[Length/@Split[IntegerDigits[#, 2]]]>1&] (* Vincenzo Librandi, Feb 05 2014 *)

PROG

(PARI) is(n)=my(t); if(n%2, t=valuation(n+1, 2); if(t==1, return(0)); n>>=t); while(n, t=valuation(n, 2); if(t==1, return(0)); n>>=t; t=valuation(n+1, 2); if(t==1, return(0)); n>>=t); 1 \\ Charles R Greathouse IV, Mar 29 2013

(PARI) is_A033015(n)={ if(1<t=valuation(n, 2), n && is_A033015(n>>t), !t && (t=valuation(n+1, 2))>1 && (n+1==(1<<t) || is_A033015(n>>t)))} \\ M. F. Hasler, Feb 01 2014

CROSSREFS

See A033001 for further cross-references.

Sequence in context: A310236 A296094 A075895 * A225574 A317305 A096998

Adjacent sequences:  A033012 A033013 A033014 * A033016 A033017 A033018

KEYWORD

nonn,base

AUTHOR

Clark Kimberling

EXTENSIONS

Extended by Ray Chandler, Dec 18 2009

STATUS

approved

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Last modified November 18 19:48 EST 2019. Contains 329288 sequences. (Running on oeis4.)