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A056980
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Number of blocks of {1, 1, 0} in binary expansion of n.
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11
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0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 2
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OFFSET
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1,54
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COMMENTS
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a(n) = A213629(n,6) for n > 5. - Reinhard Zumkeller, Jun 17 2012
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LINKS
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_Reinhard Zumkeller_, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, DigitBlock
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FORMULA
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a(2n) = a(n) + [n congruent to 3 mod 4], a(2n+1) = a(n). - Ralf Stephan, Aug 22 2003
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MATHEMATICA
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a[1] = a[2] = 0; a[n_] := a[n] = If[OddQ[n], a[(n - 1)/2], a[n/2] + Boole[Mod[n/2, 4] == 3]]; Table[a[n], {n, 1, 102}] (* Jean-François Alcover, Oct 22 2012, after Ralf Stephan *)
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PROG
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(Haskell)
import Data.List (tails, isPrefixOf)
a056980 = sum . map (fromEnum . ([0, 1, 1] `isPrefixOf`)) .
tails . a030308_row
-- Reinhard Zumkeller, Jun 17 2012
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CROSSREFS
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Cf. A014082, A056974, A056975, A056976, A056977, A056978, A056979, A056980.
Sequence in context: A176046 A172090 A037912 * A005094 A121372 A123706
Adjacent sequences: A056977 A056978 A056979 * A056981 A056982 A056983
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KEYWORD
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nonn,easy
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AUTHOR
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Eric W. Weisstein
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STATUS
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approved
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