%I A118272
%S A118272 1,2,1,4,8,6,6,8,14,10,1,16,20,14,12,16,31,18,8,20,32,28,18,24,38,32,6,
%T A118272 28,44,30,24,40,57,34,14,36,72,38,30,48,62,52,1,44,68,46,48,56,74,50,20,
%U A118272 64,80,64,42,56,108,58,12,60,112,76,48,64,98,66,31,80,104,80,54,88
%V A118272 1,-2,1,-4,8,-6,6,-8,14,-10,1,-16,20,-14,12,-16,31,-18,8,-20,32,-28,18,
               -24,38,-32,6,
%W A118272 -28,44,-30,24,-40,57,-34,14,-36,72,-38,30,-48,62,-52,1,-44,68,-46,48,
               -56,74,-50,20,
%X A118272 -64,80,-64,42,-56,108,-58,12,-60,112,-76,48,-64,98,-66,31,-80,104,-80,
               54,-88
%N A118272 Expansion of q^(-2/3)(eta(q)eta(q^3)eta(q^6)/eta(q^2))^2 in powers of 
               q.
%F A118272 Euler transform of period 6 sequence [ -2, 0, -4, 0, -2, -4, ...].
%F A118272 A118271(3n+2)=-3a(n).
%o A118272 (PARI) {a(n)=local(A); if(n<0, 0, A=x*O(x^n); polcoeff( (eta(x+A)*eta(x^3+A)*eta(x^6+A)/
               eta(x^2+A))^2, n))}
%Y A118272 Sequence in context: A059146 A059148 A158451 this_sequence A112173 A058543 
               A156817
%Y A118272 Adjacent sequences: A118269 A118270 A118271 this_sequence A118273 A118274 
               A118275
%K A118272 sign
%O A118272 0,2
%A A118272 Michael Somos, Apr 21 2006