OFFSET
1,2
LINKS
Harry J. Smith and Donovan Johnson, Table of n, a(n) for n = 1..500 (first 250 terms from Harry J. Smith)
MATHEMATICA
Select[Range[1, 10^6], DivisorSigma[1, EulerPhi[DivisorSigma[1, # ]]] == DivisorSigma[1, # ] &]
PROG
(PARI) { n=0; for (m=1, 10^10, if (sigma(eulerphi(sigma(m))) == sigma(m), write("b066471.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 17 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Joseph L. Pe, Jan 02 2002
STATUS
approved