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 A179868 (Number of 1's in the binary expansion of n) mod 4. 2
 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 0, 1, 2, 2, 3, 2, 3, 3, 0, 2, 3, 3, 0, 3, 0, 0, 1, 1, 2, 2, 3, 2, 3, 3, 0, 2, 3, 3, 0, 3, 0, 0, 1, 2, 3, 3, 0, 3, 0, 0, 1, 3, 0, 0, 1, 0, 1, 1, 2, 1, 2, 2, 3, 2, 3, 3, 0, 2, 3, 3, 0, 3, 0, 0, 1, 2, 3, 3, 0, 3, 0, 0, 1, 3, 0, 0, 1, 0, 1, 1, 2, 2, 3, 3, 0, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS This is the generalized Thue-Morse sequence t_4 (Allouche and Shallit, p. 335). REFERENCES J.-P. Allouche and J. Shallit, Automatic Sequences, Cambridge Univ. Press, 2003. LINKS Table of n, a(n) for n=0..100. FORMULA a(n) = A010873(A000120(n)). MATHEMATICA Nest[ Flatten[ # /. {0 -> {0, 1}, 1 -> {1, 2}, 2 -> {2, 3}, 3 -> {3, 0}}] &, {0}, 7] (* Robert G. Wilson v, May 17 2014 *) Table[Mod[DigitCount[n, 2, 1], 4], {n, 0, 110}] (* Harvey P. Dale, Jul 24 2016 *) PROG (PARI) a(n)=hammingweight(n)%4 \\ Charles R Greathouse IV, May 09 2016 CROSSREFS Cf. A000120, A010873, A010060 (mod 2), A071858 (mod 3). Sequence in context: A144016 A354582 A359312 * A104232 A072086 A180094 Adjacent sequences: A179865 A179866 A179867 * A179869 A179870 A179871 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Jan 11 2011 STATUS approved

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Last modified February 21 04:08 EST 2024. Contains 370219 sequences. (Running on oeis4.)