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A236627
Number of positive integers <= sqrt(n) not dividing n.
1
0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 2, 0, 2, 1, 1, 1, 3, 1, 3, 1, 2, 2, 3, 0, 3, 3, 3, 2, 4, 1, 4, 2, 3, 3, 3, 1, 5, 4, 4, 2, 5, 2, 5, 3, 3, 4, 5, 1, 5, 4, 5, 4, 6, 3, 5, 3, 5, 5, 6, 1, 6, 5, 4, 4, 6, 4, 7, 5, 6, 4, 7, 2, 7, 6, 5, 5, 6, 4, 7, 3, 6, 7, 8, 3, 7, 7, 7, 5, 8, 3, 7, 6, 7, 7, 7, 3, 8, 6, 6, 5, 9
OFFSET
1,11
COMMENTS
It appears that the indices of the zeros in the sequence are in A018253.
FORMULA
a(n) = A000196(n) - A038548(n) = A160812(n)/2.
PROG
(PARI) a(n) = sum(i=1, sqrtint(n), (n % i) != 0); \\ Michel Marcus, Mar 16 2014
KEYWORD
nonn
AUTHOR
Omar E. Pol, Feb 05 2014
STATUS
approved