OFFSET
1,2
COMMENTS
If p is prime, a(p) = Sum_{d|p} d^phi(p/d) = 1^(p-1) + p^1 = p + 1.
EXAMPLE
a(6) = Sum_{d|6} d^phi(6/d) = 1^phi(6) + 2^phi(3) + 3^phi(2) + 6^phi(1) = 14.
MATHEMATICA
Table[Sum[k^EulerPhi[n/k^(1 - Ceiling[n/k] + Floor[n/k])] (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 80}]
PROG
(PARI) a(n) = sumdiv(n, d, d^eulerphi(n/d)); \\ Michel Marcus, May 21 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, May 20 2021
STATUS
approved