OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..300
MATHEMATICA
uphi[n_] := Times@@(Power@@#-1&/@FactorInteger[n]); For[x=1, True, x++, If[uphi[y=x-(u=uphi[x])]==u, Print[{x, y}]]]
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Edited by Dean Hickerson, Mar 07 2002
Offset corrected by Donovan Johnson, May 04 2013
STATUS
approved