G.f. (4*x+3)/(2*(x+1))*(1+1/sqrt(-4*x^4-4*x^3+1)).

Terms

a(0) =3a(1) =1a(2) =-1a(3) =4a(4) =3a(5) =1a(6) =8a(7) =22a(8) =11a(9) =31a(10) =99a(11) =111a(12) =144a(13) =456a(14) =734a(15) =904a(16) =2155a(17) =4285a(18) =5921a(19) =11173a(20) =23603a(21) =37489a(22) =63161a(23) =129031a(24) =227072a(25) =375376a(26) =719432a(27) =1335478a(28) =2264118a(29) =4126266