cp's OEIS Frontend

A305808 Dirichlet convolution of A032742 (the largest proper divisor of n) with itself.

%I A305808 #6 Jun 13 2018 23:11:09
%S A305808 1,2,2,5,2,8,2,12,7,12,2,22,2,16,12,28,2,30,2,34,16,24,2,56,11,28,24,
%T A305808 46,2,56,2,64,24,36,16,87,2,40,28,88,2,76,2,70,46,48,2,136,15,70,36,
%U A305808 82,2,108,24,120,40,60,2,172,2,64,62,144,28,116,2,106,48,108,2,228,2,76,70,118,24,136,2,216,81,84,2,236,36,88,60,184,2,228,28
%N A305808 Dirichlet convolution of A032742 (the largest proper divisor of n) with itself.
%H A305808 Antti Karttunen, <a href="/A305808/b305808.txt">Table of n, a(n) for n = 1..65537</a>
%F A305808 a(n) = Sum_{d|n} A032742(n/d)*A032742(d).
%o A305808 (PARI)
%o A305808 A032742(n) = if(1==n,n,n/vecmin(factor(n)[,1]));
%o A305808 A305808(n) = sumdiv(n,d,A032742(n/d)*A032742(d));
%Y A305808 Cf. A032742, A300236, A300239, A305807.
%K A305808 nonn
%O A305808 1,2
%A A305808 _Antti Karttunen_, Jun 13 2018