OFFSET
1,2
COMMENTS
Most of these numbers are prime. The first four composites are 289, 2329, 4369, and 4913.
LINKS
T. D. Noe, Table of n, a(n) for n=1..1000
MATHEMATICA
kMax=2*3*5*7*11*13; t=Table[0, {kMax}]; Do[e=EulerPhi[k]; t[[k]]=e+t[[e]], {k, 2, kMax}]; mx=-1; Reap[Do[If[t[[k]]>mx, mx=t[[k]]; Sow[k]], {k, kMax}]][[2, 1]]
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Nov 04 2010
STATUS
approved