Expansion of g.f. (1-x+2*x^2)/((1-x)*(1-2*x-x^2)).

Terms

a(0) =1a(1) =2a(2) =7a(3) =18a(4) =45a(5) =110a(6) =267a(7) =646a(8) =1561a(9) =3770a(10) =9103a(11) =21978a(12) =53061a(13) =128102a(14) =309267a(15) =746638a(16) =1802545a(17) =4351730a(18) =10506007a(19) =25363746a(20) =61233501a(21) =147830750a(22) =356895003a(23) =861620758a(24) =2080136521a(25) =5021893802a(26) =12123924127a(27) =29269742058a(28) =70663408245a(29) =170596558550