A335060 - OEIS

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A335060

a(n) is the number of values of k < n for which 4*(a(k) + a(n-k)) < n.

0, 1, 0, 2, 2, 1, 2, 0, 4, 4, 2, 5, 6, 4, 2, 3, 10, 8, 6, 2, 6, 9, 6, 4, 8, 8, 8, 4, 12, 9, 10, 7, 10, 14, 10, 6, 8, 14, 14, 11, 12, 8, 16, 10, 14, 10, 16, 15, 14, 14, 16, 14, 12, 10, 16, 11, 18, 16, 14, 22, 20, 12, 12, 17, 24, 18, 22, 18, 22, 16, 10, 19, 26, 23, 18, 22, 24

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

LINKS

Samuel B. Reid, Table of n, a(n) for n = 1..10000

Samuel B. Reid, C program for A335060

Samuel B. Reid, Plot of 2000000 terms

EXAMPLE

a(6) is 1 because, if (a(k) + a(6-k)) * 4 is less than 6, k can only be 3.

a(9) is 4 because k must be 1, 3, 6, or 8 in order for (a(k) + a(9-k)) * 4 to be less than 9.

PROG

(PARI) lista(nn) = {my(va=vector(nn)); for (n=2, nn, va[n] = sum(k=1, n-1, 4*(va[k] + va[n-k]) < n); ); va; } \\ Michel Marcus, May 22 2020