Expansion of g.f.: (1+x-sqrt(1-2*x-7*x^2-8*x^3-4*x^4))/(2*(1+x+x^2)).

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =17a(5) =54a(6) =178a(7) =606a(8) =2116a(9) =7533a(10) =27242a(11) =99799a(12) =369583a(13) =1381309a(14) =5203599a(15) =19737935a(16) =75321337a(17) =288968031a(18) =1113893815a(19) =4312073256a(20) =16756934181a(21) =65345024968a(22) =255625711296