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 A123466 Write the positive integer n in binary. Subdivide the binary n into runs each consisting entirely of 0's or of 1's, where the runs alternate between those of 1's and those of 0's. The sequence gives those numbers n such that there is at least one run of 1's of the same length as at least one run of 0's. 2
 2, 5, 10, 11, 12, 13, 18, 19, 20, 21, 22, 23, 25, 26, 29, 34, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 50, 51, 52, 53, 56, 58, 61, 66, 69, 70, 71, 74, 75, 76, 77, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 98, 100, 101, 102, 103, 104 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 FORMULA a(n) ~ n. - Charles R Greathouse IV, Mar 29 2013 EXAMPLE 25 written in binary is 11001. The runs are (11)(00)(1). Since at least one run of 1's (the leftmost run here) is the same length as at least one run of 0's (the only run of 0's here), 25 is included in this sequence. PROG (PARI) is(n)=my(ones=List(), zeros=List()); if(n%2, listput(ones, valuation(n+1, 2)); n>>=ones[1]); while(n, listput(zeros, valuation(n, 2)); n>>=zeros[#zeros]; listput(ones, valuation(n+1, 2)); n>>=ones[#ones]); #setintersect(vecsort(Vec(ones), , 8), vecsort(Vec(zeros), , 8))>0 \\ Charles R Greathouse IV, Mar 29 2013 CROSSREFS Cf. A033015. Sequence in context: A138848 A194350 A182179 * A144793 A140707 A257086 Adjacent sequences:  A123463 A123464 A123465 * A123467 A123468 A123469 KEYWORD base,easy,nonn AUTHOR Leroy Quet, Jul 11 2008 EXTENSIONS a(16) to a(27) from Ray G. Opao, Jan 08 2009 a(28)-a(64) from Lars Blomberg, Dec 09 2011 STATUS approved

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Last modified August 14 09:27 EDT 2022. Contains 356110 sequences. (Running on oeis4.)