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A062401 a(n) = phi(sigma(n)). 62

%I

%S 1,2,2,6,2,4,4,8,12,6,4,12,6,8,8,30,6,24,8,12,16,12,8,16,30,12,16,24,

%T 8,24,16,36,16,18,16,72,18,16,24,24,12,32,20,24,24,24,16,60,36,60,24,

%U 42,18,32,24,32,32,24,16,48,30,32,48,126,24,48,32,36,32,48,24,96,36,36,60

%N a(n) = phi(sigma(n)).

%D D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 14.

%H T. D. Noe, <a href="/A062401/b062401.txt">Table of n, a(n) for n = 1..10000</a>

%F sigma(a(n)) = A062402(sigma(n)) or phi(A062402(n)) = a(phi(n)). - _Labos Elemer_, Jul 22 2004

%e a(9) = 12 because sigma(9) = 13 and phi(13) = 12.

%p with(numtheory); A062401:=n->phi(sigma(n)); seq(A062401(n), n=1..50); # _Wesley Ivan Hurt_, Apr 07 2014

%t Table[EulerPhi[DivisorSigma[1, n]], {n, 1, 80}] (* _Carl Najafi_, Aug 16 2011 *)

%o (PARI) vector(150, n, eulerphi(sigma(n)))

%o (PARI) for (n=1, 10000, write("b062401.txt", n, " ", eulerphi(sigma(n))) ) \\ _Harry J. Smith_, Aug 07 2009

%o (Haskell)

%o a062401 = a000010 . a000203 -- _Reinhard Zumkeller_, Jan 04 2013

%Y Cf. A000203, A000010, A062402, A096852, A096857, A096994, A096995, A033632.

%K nonn

%O 1,2

%A _Jason Earls_, Jul 08 2001

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Last modified November 19 16:37 EST 2019. Contains 329323 sequences. (Running on oeis4.)