a(n) = A058094(n) - 3*A058094(n-1) + A058094(n-2) for n >=4.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =5a(5) =20a(6) =75a(7) =271a(8) =957a(9) =3337a(10) =11559a(11) =39896a(12) =137423a(13) =472808a(14) =1625632a(15) =5587228a(16) =19198971a(17) =65963978a(18) =226623902a(19) =778551761a(20) =2674604282a(21) =9188106871a(22) =31563807424a(23) =108430368827a(24) =372487292867