OFFSET
1,1
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..140
MATHEMATICA
NestList[DivisorSigma[1, #]+EulerPhi[#]&, 3, 30] (* Harvey P. Dale, Feb 06 2020 *)
PROG
(PARI) seq(n)={my(v=vector(n)); v[1]=3; for(i=2, n, v[i]=sigma(v[i-1]) + eulerphi(v[i-1])); v} \\ Harry J. Smith, Aug 19 2009, Andrew Howroyd, Jun 26 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Aug 09 2001
EXTENSIONS
More terms from Harry J. Smith, Aug 19 2009
STATUS
approved