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A137413 a(n) = the number of positive integers that are <= n and are coprime to (the sum of the distinct prime divisors of n). 0
1, 1, 2, 2, 4, 5, 6, 4, 6, 9, 10, 10, 12, 10, 8, 8, 16, 15, 18, 18, 9, 21, 22, 20, 20, 14, 18, 19, 28, 12, 30, 16, 15, 33, 12, 29, 36, 22, 20, 35, 40, 14, 42, 41, 23, 37, 46, 39, 42, 43, 21, 28, 52, 44, 28, 38, 26, 57, 58, 24, 60, 38, 26, 32, 22, 33, 66, 65, 32, 30, 70, 58, 72, 46 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..74.

EXAMPLE

The distinct primes dividing 21 are 3 and 7. 3+7 = 10. The positive integers that are <= 21 and are coprime to 10 are 1,3,7,9,11,13,17,19,21. There are 9 of these; so a(21) = 9.

PROG

(PARI) a(n) = local(t=if(n==1, [], factor(n)~[1, ]), s=t*vector(#t, x, 1)~, ct=0, i); for(i=1, n, if(gcd(i, s)==1, ct++)); ct \\ Hagen von Eitzen, Jun 16 2009

CROSSREFS

Cf. A008472.

Sequence in context: A085085 A121600 A126870 * A010848 A133937 A181523

Adjacent sequences:  A137410 A137411 A137412 * A137414 A137415 A137416

KEYWORD

nonn

AUTHOR

Leroy Quet, Apr 15 2008

EXTENSIONS

More terms from Hagen von Eitzen, Jun 16 2009

STATUS

approved

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Last modified July 27 21:20 EDT 2021. Contains 346316 sequences. (Running on oeis4.)