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 A014082 Number of occurrences of '111' in binary expansion of n. 15
 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 2, 3, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 3, 4, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 2, 3, 0, 0, 0, 0, 0, 0, 0, 1, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,16 COMMENTS a(n) = A213629(n,7) for n > 6. - Reinhard Zumkeller, Jun 17 2012 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 0..10000 Ralf Stephan, Some divide-and-conquer sequences ... Ralf Stephan, Table of generating functions Eric Weisstein's World of Mathematics, Digit Block FORMULA a(2n) = a(n), a(2n+1) = a(n) + [n congruent to 3 mod 4]. - Ralf Stephan, Aug 21 2003 G.f.: 1/(1-x) * Sum_{k>=0} t^7(1-t)/(1-t^8), where t=x^2^k. - Ralf Stephan, Sep 08 2003 MAPLE See A014081. f:= proc(n) option remember;   if n::even then procname(n/2)   elif n mod 8 = 7 then 1 + procname((n-1)/2)   else procname((n-1)/2) fi end proc: f(0):= 0: map(f, [\$0..1000]); # Robert Israel, Sep 11 2015 MATHEMATICA f[n_] := Count[ Partition[ IntegerDigits[n, 2], 3, 1], {1, 1, 1}]; Table[f@n, {n, 0, 104}] (* Robert G. Wilson v, Apr 02 2009 *) a[0] = a[1] = 0; a[n_] := a[n] = If[EvenQ[n], a[n/2], a[(n - 1)/2] + Boole[Mod[(n - 1)/2, 4] == 3]]; Table[a[n], {n, 0, 104}] (* Jean-François Alcover, Oct 22 2012, after Ralf Stephan *) PROG (Haskell) import Data.List (tails, isPrefixOf) a014082 = sum . map (fromEnum . ([1, 1, 1] `isPrefixOf`)) .                     tails . a030308_row -- Reinhard Zumkeller, Jun 17 2012 (PARI) a(n) = hammingweight(bitand(n, bitand(n>>1, n>>2))); \\ Gheorghe Coserea, Aug 30 2015 CROSSREFS Cf. A014081, A033264, A056974, A056975, A056976, A056977, A056978, A056979, A056980, A213629, A239906, A239907. Sequence in context: A010103 A086078 A323913 * A322583 A102354 A157228 Adjacent sequences:  A014079 A014080 A014081 * A014083 A014084 A014085 KEYWORD nonn,easy,base AUTHOR STATUS approved

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Last modified September 20 21:09 EDT 2019. Contains 327247 sequences. (Running on oeis4.)