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A175732 a(n) = gcd(phi(n), psi(n)). 1
1, 1, 2, 2, 2, 2, 2, 4, 6, 2, 2, 4, 2, 6, 8, 8, 2, 6, 2, 4, 4, 2, 2, 8, 10, 6, 18, 12, 2, 8, 2, 16, 4, 2, 24, 12, 2, 6, 8, 8, 2, 12, 2, 4, 24, 2, 2, 16, 14, 10, 8, 12, 2, 18, 8, 24, 4, 2, 2, 16, 2, 6, 12, 32, 12, 4, 2, 4, 4, 24, 2, 24, 2, 6, 40, 12, 12, 24, 2, 16, 54, 2, 2, 24, 4, 6, 8, 8, 2, 24, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(n)^2 divides J_2(n), where J_2 is A007434.

If p > 2 is a prime, a(n) = 2. - Enrique Pérez Herrero, Jan 02 2012

LINKS

Enrique Pérez Herrero, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = gcd(A000010(n), A001615(n)).

a(n) >= (n*2^(omega(n)-1))/rad(n).

a(A002110(n)) = A078558(n). - Enrique Pérez Herrero, Dec 04 2012

MATHEMATICA

JordanTotient[n_, k_:1] := DivisorSum[n, #^k * MoebiusMu[n/#] &] /; (n > 0) && IntegerQ[n]; DedekindPsi[n_] := JordanTotient[n, 2]/EulerPhi[n]; A175732[n_] := GCD[EulerPhi[n], DedekindPsi[n]]; Array[A175732, 100]

CROSSREFS

Cf. A000010, A001615, A007434.

Sequence in context: A294226 A083499 A029103 * A327817 A168260 A008737

Adjacent sequences:  A175729 A175730 A175731 * A175733 A175734 A175735

KEYWORD

nonn

AUTHOR

Enrique Pérez Herrero, Aug 24 2010

STATUS

approved

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Last modified January 16 06:41 EST 2021. Contains 340204 sequences. (Running on oeis4.)