a(n) = 4*a(n-1) -3*a(n-2) -2*a(n-3) +a(n-4), n>8.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =0a(5) =4a(6) =17a(7) =55a(8) =161a(9) =449a(10) =1220a(11) =3266a(12) =8667a(13) =22879a(14) =60203a(15) =158107a(16) =414728a(17) =1087064a(18) =2848061a(19) =7459703a(20) =19535229a(21) =51152749a(22) =133933964a(23) =350666854a(24) =918095255a(25) =2403665279a(26) =6292975607a(27) =16475382935a(28) =43133369616a(29) =112925043724