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%I #12 Aug 02 2018 11:54:24
%S 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,
%T 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,
%U 19,6,13,4,19,12,25,20,23,10,19,10,21,16,23,10
%N a(n) = number of k with 1 <= k <= n-1 such that abs(a(k) - a(n-k)) <= 2.
%C See A317420 for similar sequences.
%H Rémy Sigrist, <a href="/A317585/b317585.txt">Table of n, a(n) for n = 1..10000</a>
%H Rémy Sigrist, <a href="/A317585/a317585.png">Colored scatterplot of the first 100000 terms</a> (where the color is function of the parity of n)
%F For n = 5:
%F - |a(1) - a(4)| = |0 - 3| = 3 > 2,
%F - |a(2) - a(3)| = |1 - 2| = 1 <= 2,
%F - |a(3) - a(2)| = |2 - 1| = 1 <= 2,
%F - |a(4) - a(1)| = |3 - 0| = 3 > 2,
%F - hence a(5) = 2.
%o (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] ", "))
%Y Cf. A317420.
%K nonn
%O 1,3
%A _Rémy Sigrist_, Aug 01 2018