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A062401
a(n) = phi(sigma(n)).
107
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, 8, 24, 16, 36, 16, 18, 16, 72, 18, 16, 24, 24, 12, 32, 20, 24, 24, 24, 16, 60, 36, 60, 24, 42, 18, 32, 24, 32, 32, 24, 16, 48, 30, 32, 48, 126, 24, 48, 32, 36, 32, 48, 24, 96, 36, 36, 60
OFFSET
1,2
REFERENCES
D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 14.
FORMULA
sigma(a(n)) = A062402(sigma(n)) or phi(A062402(n)) = a(phi(n)). - Labos Elemer, Jul 22 2004
EXAMPLE
a(9) = 12 because sigma(9) = 13 and phi(13) = 12.
MAPLE
with(numtheory); A062401:=n->phi(sigma(n)); seq(A062401(n), n=1..50); # Wesley Ivan Hurt, Apr 07 2014
MATHEMATICA
Table[EulerPhi[DivisorSigma[1, n]], {n, 1, 80}] (* Carl Najafi, Aug 16 2011 *)
PROG
(PARI) vector(150, n, eulerphi(sigma(n)))
(PARI) for (n=1, 10000, write("b062401.txt", n, " ", eulerphi(sigma(n))) ) \\ Harry J. Smith, Aug 07 2009
(Haskell)
a062401 = a000010 . a000203 -- Reinhard Zumkeller, Jan 04 2013
CROSSREFS
Cf. A001229 (fixed points).
Sequence in context: A021446 A353754 A353752 * A286383 A138949 A138951
KEYWORD
nonn
AUTHOR
Jason Earls, Jul 08 2001
STATUS
approved