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 A292597 a(1) = 1; for n > 1, a(n) = c(n) + 2*a(floor(n/2)), where c(n) is the characteristic function of odd composites, A071904. 2
 1, 2, 2, 4, 4, 4, 4, 8, 9, 8, 8, 8, 8, 8, 9, 16, 16, 18, 18, 16, 17, 16, 16, 16, 17, 16, 17, 16, 16, 18, 18, 32, 33, 32, 33, 36, 36, 36, 37, 32, 32, 34, 34, 32, 33, 32, 32, 32, 33, 34, 35, 32, 32, 34, 35, 32, 33, 32, 32, 36, 36, 36, 37, 64, 65, 66, 66, 64, 65, 66, 66, 72, 72, 72, 73, 72, 73, 74, 74, 64, 65, 64, 64, 68, 69, 68, 69, 64, 64, 66, 67 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 1-bits in base-2 expansion of a(n) indicate the positions of odd nonprimes in the sequence [n, floor(n/2), floor(n/4), ..., 1]. LINKS Antti Karttunen, Table of n, a(n) for n = 1..16384 FORMULA a(1) = 1; for n > 1, a(n) = (A000035(n)*(1-A010051(n))) + 2*a(floor(n/2)). For all n >= 1, a(n) + A292596(n) = n. PROG (Scheme, with memoization-macro definec) (definec (A292597 n) (if (= 1 n) 1 (+ (* (A000035 n) (- 1 (A010051 n))) (* 2 (A292597 (floor->exact (/ n 2))))))) CROSSREFS Cf. A000035, A010051, A014076, A071904, A292596, A292598. Sequence in context: A039593 A327649 A265529 * A101656 A090557 A230875 Adjacent sequences:  A292594 A292595 A292596 * A292598 A292599 A292600 KEYWORD nonn AUTHOR Antti Karttunen, Sep 27 2017 STATUS approved

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Last modified January 19 20:41 EST 2020. Contains 331066 sequences. (Running on oeis4.)