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A102448 a(n) is the number of ways to write n = k^2 * j, j <= k, gcd(k,j) = 1, where j and k are positive integers.

%I A102448 #20 Aug 27 2017 12:55:24
%S A102448 1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,
%T A102448 0,1,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,
%U A102448 0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,2,0,0,0,0,0
%N A102448 a(n) is the number of ways to write n = k^2 * j, j <= k, gcd(k,j) = 1, where j and k are positive integers.
%C A102448 Sum_{n>0} a(n)/n = 2.
%H A102448 Antti Karttunen, <a href="/A102448/b102448.txt">Table of n, a(n) for n = 1..65537</a>
%F A102448 a(n) <= A102354(n). - _Antti Karttunen_, Aug 27 2017
%e A102448 a(18) = 1 because 18 = k^2 * j, j <= k, gcd(k,j)=1, in one way: k=3, j=2.
%t A102448 t = Sort[ Flatten[ Table[ If[ GCD[j, k] == 1, k^2*j, {}], {k, 11}, {j, k}]]]; Table[ Count[t, n], {n, 105}] (* _Robert G. Wilson v_, Feb 25 2005 *)
%o A102448 (PARI) A102448(n) = sumdiv(n,d,((1==gcd(d,(n/d))) && issquare(d) && (sqrtint(d) >= (n/d)))); \\ _Antti Karttunen_, Aug 27 2017
%Y A102448 Cf. A102354, A104021, A104023, A104025.
%K A102448 nonn
%O A102448 1,100
%A A102448 _Leroy Quet_, Feb 23 2005
%E A102448 More terms from _Robert G. Wilson v_, Feb 24 2005