OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..2000
Stefan Porubsky and M. G. Greening, Problem E2351, Amer. Math. Monthly, Vol. 80, No. 4 (1973), p. 436.
FORMULA
Multiplicative with a(p^e) = (e+1)^2*(p-1)*p^(e-1). - Amiram Eldar, Dec 29 2022
EXAMPLE
a(4)=18 because phi(4)=2 and tau(4)=3.
MAPLE
with(numtheory): a:=n->phi(n)*tau(n)^2: seq(a(n), n=1..70);
MATHEMATICA
Table[EulerPhi[n]DivisorSigma[0, n]^2, {n, 60}] (* Harvey P. Dale, Nov 29 2011 *)
PROG
(PARI) a(n) = eulerphi(n)*numdiv(n)^2; \\ Michel Marcus, Jun 21 2017
(Magma) [EulerPhi(n)*NumberOfDivisors(n)^2: n in [1..60]]; // Vincenzo Librandi, Jun 21 2017
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Emeric Deutsch, Jul 29 2005
STATUS
approved