%I A093067
%S A093067 1,2,1,4,3,2,11,6,11,20,15,16,43,24,32,76,48,58,144,84,97,238,144,172,
%T A093067 398,234,279,636,372,428,1012,582,678,1564,906,1028,2389,1362,1576,3560,
%U A093067 2046,2320,5290,2988,3407,7700,4371,4928
%V A093067 1,-2,-1,4,-3,-2,11,-6,-11,20,-15,-16,43,-24,-32,76,-48,-58,144,-84,-97,
               238,-144,-172,
%W A093067 398,-234,-279,636,-372,-428,1012,-582,-678,1564,-906,-1028,2389,-1362,
               -1576,3560,
%X A093067 -2046,-2320,5290,-2988,-3407,7700,-4371,-4928
%N A093067 Expansion of (eta(q)eta(q^5)/(eta(q^3)eta(q^15)))^2 in powers of q.
%C A093067 Euler transform of period 15 sequence [ -2,-2,0,-2,-4,0,-2,-2,0,-4,-2,
               0,-2,-2,0,...].
%C A093067 G.f. A(x)=y satisfies 0=f(A(x),A(x^2)) where f(u,v)=u^3+v^3-4uv(u+v)-u^2v^2-9uv.
%o A093067 (PARI) a(n)=local(X); if(n<-1,0,n++; X=x+x*O(x^n); polcoeff((eta(X)*eta(X^5)/
               eta(X^3)/eta(X^15))^2,n))
%o A093067 (PARI) a(n)=local(A,u,v);if(n<-1,0,A=1/x; for(k=0,n,u=A+x*O(x^k); v=subst(u,
               x,x^2); A+=x^k*polcoeff(u^3+v^3-4*u*v*(u+v)-u^2*v^2-9*u*v,k-5)/2); 
               polcoeff(A,n))
%Y A093067 Apart from constant term, same as A058509.
%Y A093067 Sequence in context: A140169 A124731 A143122 this_sequence A098122 A159931 
               A159755
%Y A093067 Adjacent sequences: A093064 A093065 A093066 this_sequence A093068 A093069 
               A093070
%K A093067 sign
%O A093067 -1,2
%A A093067 Michael Somos, Mar 17 2004