a(n) = 2*A058094(n-2) - 5*A058094(n-3) + A058094(n-4) + a(n-1) for n >=4.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =6a(6) =25a(7) =93a(8) =333a(9) =1172a(10) =4083a(11) =14137a(12) =48778a(13) =167981a(14) =577874a(15) =1986747a(16) =6828120a(17) =23462470a(18) =80611581a(19) =276944893a(20) =951422603a(21) =3268470411a(22) =11228209786a(23) =38572124196a(24) =132505812826a(25) =455192771711