

A107654


Numbers n such that if sum of the proper divisors of n is equal to m then n = phi(m).


1




OFFSET

1,1


COMMENTS

Next term is greater than 65*10^6.
241287413760 and 6094936793088000 are also terms  Donovan Johnson, Aug 08 2012


LINKS

Table of n, a(n) for n=1..8.


EXAMPLE

62000640 is in the sequence because sigma(62000640)62000640 = 187545888 and phi(187545888) = 62000640.


MATHEMATICA

Do[If[n == EulerPhi[DivisorSigma[1, n]n], Print[n]], {n, 65000000}]


CROSSREFS

Cf. A107653.
Sequence in context: A191303 A291869 A186849 * A345611 A346328 A345620
Adjacent sequences: A107651 A107652 A107653 * A107655 A107656 A107657


KEYWORD

more,nonn


AUTHOR

Farideh Firoozbakht, May 26 2005


EXTENSIONS

a(7) from Donovan Johnson, Oct 12 2008
a(8) from Donovan Johnson, Aug 08 2012


STATUS

approved



