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 A317419 a(n) = number of k with 1 <= k <= n-1 such that a(k) AND a(n-k) = 0 (where AND denotes the bitwise AND operator). 2
 0, 1, 2, 2, 4, 4, 4, 6, 8, 8, 6, 6, 8, 8, 8, 10, 12, 12, 10, 14, 20, 14, 8, 10, 12, 12, 8, 8, 12, 14, 14, 10, 10, 12, 12, 8, 10, 14, 16, 12, 6, 10, 12, 14, 8, 8, 12, 14, 14, 14, 14, 10, 12, 12, 8, 12, 18, 16, 12, 8, 10, 14, 18, 14, 10, 18, 18, 16, 12, 14, 18 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS All terms are even except a(2) = 1. See A317420 for similar sequences. LINKS Rémy Sigrist, Table of n, a(n) for n = 1..10000 EXAMPLE For n = 4: - a(1) AND a(3) = 0 AND 2 = 0, - a(2) AND a(2) = 1 AND 1 = 1 <> 0, - a(3) AND a(1) = 2 AND 0 = 0, - hence a(4) = 2. PROG (PARI) a = vector(71); for (n=1, #a, a[n] = sum(k=1, n-1, bitand(a[k], a[n-k])==0); print1 (a[n] ", ")) CROSSREFS Cf. A317420. Sequence in context: A333787 A062570 A108514 * A364843 A372678 A120456 Adjacent sequences: A317416 A317417 A317418 * A317420 A317421 A317422 KEYWORD nonn,base AUTHOR Rémy Sigrist, Jul 27 2018 STATUS approved

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Last modified September 18 20:35 EDT 2024. Contains 376002 sequences. (Running on oeis4.)