a(0) = 1, a(1) = 2; for n>0, a(2*n) = 3*a(2*n-1) - a(2*n-2), a(2*n+1) = 3*a(2*n) - a(2*n-1) - a(n-1).

A129804

a(0) = 1, a(1) = 2; for n>0, a(2*n) = 3*a(2*n-1) - a(2*n-2), a(2*n+1) = 3*a(2*n) - a(2*n-1) - a(n-1).

Terms

    a(0) =1a(1) =2a(2) =5a(3) =12a(4) =31a(5) =79a(6) =206a(7) =534a(8) =1396a(9) =3642a(10) =9530a(11) =24917a(12) =65221a(13) =170667a(14) =446780a(15) =1169467a(16) =3061621a(17) =8014862a(18) =20982965a(19) =54932637a(20) =143814946a(21) =376508559a(22) =985710731a(23) =2580614104a(24) =6756131581a(25) =17687755722a(26) =46307135585a(27) =121233585812

External references