OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..100
EXAMPLE
phi(24066)*24066 = 164611440 = T(18144).
MATHEMATICA
Select[Range[2.6*10^6], OddQ[Sqrt[8#*EulerPhi[#]+1]]&] (* Harvey P. Dale, Jul 11 2017 *)
PROG
(PARI) isok(n) = ispolygonal(n*eulerphi(n), 3); \\ Michel Marcus, Jan 25 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, Feb 06 2006
STATUS
approved