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A179179 a(n) = phi(n) - omega(n) = A000010(n) - A001221(n). 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified September 22 00:25 EDT 2017. Contains 292326 sequences.