%I A029935
%S A029935 1,2,4,5,8,8,12,12,16,16,20,20,24,24,32,28,32,32,36,40,
%T A029935 48,40,44,48,56,48,60,60,56,64,60,64,80,64,96,80,72,72,
%U A029935 96,96,80,96,84,100,128,88,92,112,120,112,128,120,104,120
%N A029935 Sum phi(d)*phi(n/d); d divides n.
%C A029935 Sum_{d|n} a_d = A018804(n). - Frank Adams-Watters (FrankTAW(AT)Netscape.net), 
               Nov 19 2004
%C A029935 Equals row sums of triangle A159937 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), 
               Apr 26 2009]
%F A029935 Sum_{k=1..n} phi(gcd(n, k)). Multiplicative with a(p^e) = (e+1)*(p^e 
               - p^(e - 1)) - (e - 1)*(p^(e - 1) - p^(e - 2)). - Vladeta Jovovic 
               (vladeta(AT)eunet.rs), Oct 30 2001
%F A029935 Dirichlet g.f.: zeta(s-1)^2/zeta(s)^2. - Frank Adams-Watters (FrankTAW(AT)Netscape.net), 
               Nov 19 2004
%F A029935 Equals A051731 (inverse Mobius transform) of A018804: (1, 3, 5, 8, 9, 
               15, 13,...); and row sums of triangle A143258. [From Gary W. Adamson 
               (qntmpkt(AT)yahoo.com), Aug 02 2008]
%p A029935 with(numtheory): A029935 := proc(n) local i,j; j := 0; for i in divisors(n) 
               do j := j+phi(i)*phi(n/i); od; j; end;
%Y A029935 Cf. A029936.
%Y A029935 A159937 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Apr 26 2009]
%Y A029935 Sequence in context: A036694 A085624 A061884 this_sequence A123291 A099402 
               A117070
%Y A029935 Adjacent sequences: A029932 A029933 A029934 this_sequence A029936 A029937 
               A029938
%K A029935 mult,nonn
%O A029935 1,2
%A A029935 N. J. A. Sloane (njas(AT)research.att.com).