a(1)=0; thereafter a(n) = A238824(n-1)+A238830(n-1).

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =4a(5) =9a(6) =23a(7) =58a(8) =141a(9) =353a(10) =861a(11) =2134a(12) =5236a(13) =12924a(14) =31798a(15) =78382a(16) =193029a(17) =475619a(18) =1171600a(19) =2886427a(20) =7110657a(21) =17517598a(22) =43154977a(23) =106314193a(24) =261908415a(25) =645221312a(26) =1589525242a(27) =3915853416a(28) =9646844896a(29) =23765351096