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A176095 a(n) = n - phi(2*n), where phi() is the Euler totient A000010(). 2
0, 0, 1, 0, 1, 2, 1, 0, 3, 2, 1, 4, 1, 2, 7, 0, 1, 6, 1, 4, 9, 2, 1, 8, 5, 2, 9, 4, 1, 14, 1, 0, 13, 2, 11, 12, 1, 2, 15, 8, 1, 18, 1, 4, 21, 2, 1, 16, 7, 10, 19, 4, 1, 18, 15, 8, 21, 2, 1, 28, 1, 2, 27, 0, 17, 26, 1, 4, 25, 22, 1, 24, 1, 2, 35, 4, 17, 30, 1, 16, 27, 2, 1, 36, 21, 2, 31, 8, 1, 42, 19 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

REFERENCES

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 840.

T. M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1976, page 24.

LINKS

Table of n, a(n) for n=1..91.

FORMULA

a(n) = n - A062570(n).

a(2^k) = 0, k>=0. [Michel Lagneau, Dec 17 2010]

a( A000040(k)) = 1, k>=1. [Michel Lagneau, Dec 17 2010]

a( 2^m*A000040(k)) = 2^m, m>=1, k>=2. [Michel Lagneau, Dec 17 2010]

EXAMPLE

a(1) = 1 - phi(2) = 0 ;

a(2) = 2 - phi(2*2) = 2 - 2 = 0 ;

a(3) = 3 - phi(2*3) = 3 - 2 = 1 ;

Example where n =(2^m)*p, with m = 3 and p = 7, then n = 7* 2^3 = 56, and a(56) = 2 ^3 = 8.

MAPLE

A176095 := proc(n)

    n-numtheory[phi](2*n) ;

end proc:

seq(A176095(n), n=1..60) ;

MATHEMATICA

Table[n-EulerPhi[2n], {n, 0, 100}] (* Harvey P. Dale, Jul 24 2011 *)

CROSSREFS

Cf. A000010

Sequence in context: A022336 A019586 A257962 * A295508 A260672 A063942

Adjacent sequences:  A176092 A176093 A176094 * A176096 A176097 A176098

KEYWORD

nonn

AUTHOR

Michel Lagneau, Apr 08 2010

EXTENSIONS

Punctuation added to examples and Offet corrected. Corrected and edited by Michel Lagneau Michel Lagneau, Apr 25 2010

STATUS

approved

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Last modified February 25 21:58 EST 2018. Contains 299660 sequences. (Running on oeis4.)