Expansion of Sum_{k>=1} x^k/(1 - x^k - 2*x^(2*k)).

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =12a(5) =26a(6) =44a(7) =92a(8) =175a(9) =354a(10) =684a(11) =1396a(12) =2732a(13) =5506a(14) =10938a(15) =21937a(16) =43692a(17) =87578a(18) =174764a(19) =349884a(20) =699098a(21) =1398786a(22) =2796204a(23) =5593886a(24) =11184823a(25) =22372354a(26) =44739418a(27) =89483996a(28) =178956972a(29) =357925242