OFFSET
1,2
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..690
Eric Weisstein's World of Mathematics, Totient Function
Wikipedia, Euler's totient function
FORMULA
a(n) = n*A027385(n).
MATHEMATICA
EulerPhi[3^Range[30] - 1] (* Paolo Xausa, Jun 18 2024 *)
PROG
(PARI) {a(n) = eulerphi(3^n-1)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 22 2017
STATUS
approved