A236627 Number of positive integers <= sqrt(n) not dividing n.

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.

Links

Table of n, a(n) for n=1..101.

Omar E. Pol, , Three illustrations of A000005 giving the structure of this sequence, (2013)

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

Crossrefs

Cf. A000005, A000196, A010052, A018253, A038548, A007491, A160812, A161205, A212119, A228813, A228814, A229940, A229942, A229944, A229950, A229951.

Sequence in context: A364259 A302242 A336915 * A116664 A295672 A308074

Adjacent sequences: A236624 A236625 A236626 * A236628 A236629 A236630

Keyword

nonn

Author

Omar E. Pol, Feb 05 2014

Status

approved