1,2

Table of n, a(n) for n=1..69.

(PARI) f(n) = sumdiv(n, d, n % (sum(m=0, n-1, Mod(m, n)^d == m)/sum(m=0, n-1, -Mod(m, n)^d == m)) == 0); \\ A337454

isok(n) = f(n) == numdiv(n);

Cf. A000005, A337454, A338189.

Sequence in context: A325397 A289812 A206551 * A247762 A343268 A107909

Adjacent sequences: A338187 A338188 A338189 * A338191 A338192 A338193

nonn

Michel Marcus, Oct 15 2020

approved