A062401 - OEIS

A062401

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

106

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

REFERENCES

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

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

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. A000203, A000010, A062402, A096852, A096857, A096994, A096995, A033632.

Cf. A001229 (fixed points).

Sequence in context: A021446 A353754 A353752 * A286383 A138949 A138951

Adjacent sequences: A062398 A062399 A062400 * A062402 A062403 A062404

KEYWORD

nonn

AUTHOR

Jason Earls, Jul 08 2001

STATUS

approved