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 A317585 a(n) = number of k with 1 <= k <= n-1 such that abs(a(k) - a(n-k)) <= 2. 2
 0, 1, 2, 3, 2, 5, 4, 3, 2, 9, 6, 7, 6, 5, 2, 5, 6, 9, 4, 9, 2, 13, 12, 13, 8, 7, 6, 11, 6, 13, 2, 9, 8, 7, 8, 13, 4, 13, 6, 15, 6, 11, 12, 13, 16, 23, 8, 13, 0, 17, 14, 25, 14, 13, 8, 7, 6, 19, 8, 19, 6, 13, 4, 19, 12, 25, 20, 23, 10, 19, 10, 21, 16, 23, 10 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS See A317420 for similar sequences. LINKS Rémy Sigrist, Table of n, a(n) for n = 1..10000 Rémy Sigrist, Colored scatterplot of the first 100000 terms (where the color is function of the parity of n) FORMULA For n = 5: - |a(1) - a(4)| = |0 - 3| = 3 > 2, - |a(2) - a(3)| = |1 - 2| = 1 <= 2, - |a(3) - a(2)| = |2 - 1| = 1 <= 2, - |a(4) - a(1)| = |3 - 0| = 3 > 2, - hence a(5) = 2. PROG (PARI) a = vector(75); for (n=1, #a, a[n] = sum(k=1, n-1, abs(a[k]-a[n-k])<=2); print1 (a[n] ", ")) CROSSREFS Cf. A317420. Sequence in context: A141663 A011153 A214750 * A132226 A197702 A075861 Adjacent sequences: A317582 A317583 A317584 * A317586 A317587 A317588 KEYWORD nonn AUTHOR Rémy Sigrist, Aug 01 2018 STATUS approved

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Last modified July 21 01:14 EDT 2024. Contains 374462 sequences. (Running on oeis4.)