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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, 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
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.)