OFFSET
0,2
FORMULA
MAPLE
a:= proc(n) uses numtheory;
add(phi(n/d)^2*2^(d+1), d=divisors(n))
end:
seq(a(n), n=0..32); # Alois P. Heinz, Jun 24 2021
PROG
(PARI) a(n) = if (n, sumdiv(n, d, eulerphi(n/d)^2*2^(d+1)), 0); \\ Michel Marcus, Jun 24 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 21 2009
STATUS
approved