OFFSET
1,2
FORMULA
G.f.: x^2/((1 + x)*(1 - x)^2) + Sum_{k>=1} mu(k)*x^k/(1 - x^k)^2. - Ilya Gutkovskiy, Jan 05 2017
MAPLE
with(numtheory): A280577:=n->phi(n)+floor(n/2): seq(A280577(n), n=1..100); # Wesley Ivan Hurt, Jan 05 2017
MATHEMATICA
Table[EulerPhi[n] + Floor[n/2], {n, 100}] (* Wesley Ivan Hurt, Jan 05 2017 *)
PROG
(PARI) a(n) = eulerphi(n) + floor(n/2);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Marcus, Jan 05 2017
STATUS
approved