a(n) = 4*a(n-1) - 6*a(n-2) + 6*a(n-3) - 3*a(n-4), with initial terms 0, 0, 0, 1.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =4a(5) =10a(6) =22a(7) =49a(8) =112a(9) =256a(10) =580a(11) =1309a(12) =2956a(13) =6682a(14) =15106a(15) =34141a(16) =77152a(17) =174352a(18) =394024a(19) =890473a(20) =2012404a(21) =4547866a(22) =10277806a(23) =23227033a(24) =52491280a(25) =118626160a(26) =268085740a(27) =605852581a(28) =1369179004a(29) =3094236490