1,4

a(n) depends only on prime signature of n (cf. A025487). So a(24) = a(375) since 24=2^3*3 and 375=3*5^3 both have prime signature (3,1).

Dirichlet g.f.: (3-2*zeta(s))/(4-3*zeta(s)).

6=((6))=((3*2))=((2*3))=((3)*(2))=((2)*(3))=((3))*((2))=((2))*((3)).

Cf. A002033, A050351-A050359. a(p^k)=4^(k-1). a(A002110)=A050352.

Sequence in context: A157259 A046551 A065814 this_sequence A158860 A037022 A037023

Adjacent sequences: A050353 A050354 A050355 this_sequence A050357 A050358 A050359

nonn

Christian G. Bower (bowerc(AT)usa.net), Oct 15 1999.