



1, 0, 1, 1, 3, 0, 5, 3, 5, 2, 9, 2, 11, 4, 6, 7, 15, 4, 17, 6, 10, 8, 21, 6, 19, 10, 17, 10, 27, 5, 29, 15, 18, 14, 22, 10, 35, 16, 22, 14, 39, 9, 41, 18, 22, 20, 45, 14, 41, 18, 30, 22, 51, 16, 38, 22, 34, 26, 57, 13, 59, 28, 34, 31, 46, 17, 65, 30, 42, 21, 69, 22, 71, 34, 38, 34, 58
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OFFSET

1,5


COMMENTS

a(n) is the number of positive integers which are coprime to n minus the number of distinct primes dividing n.


LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000
Peter Luschny, Blog on OEIS, Euler's totient function


FORMULA

a(n) = phi(n)  omega(n), by definition.


EXAMPLE

a(7) = phi(7)  omega(7) = card({1,2,3,4,5,6})  card({7}) = 6  1 = 5


MAPLE

with(numtheory): a := n > phi(n)  nops(factorset(n));


MATHEMATICA

Table[EulerPhi[n]  PrimeNu[n], {n, 1, 50}] (* G. C. Greubel, Apr 23 2017 *)


CROSSREFS

Cf. A000010, A001221, A057859.
Sequence in context: A284662 A201565 A088191 * A291503 A108500 A076109
Adjacent sequences: A179176 A179177 A179178 * A179180 A179181 A179182


KEYWORD

nonn


AUTHOR

Peter Luschny, Jun 30 2010


STATUS

approved



