a(n+3) = 6a(n+2) - 10a(n+1) + 3a(n); a(0) = 1, a(1) = 4, a(2) = 14.

Terms

a(0) =1a(1) =4a(2) =14a(3) =47a(4) =154a(5) =496a(6) =1577a(7) =4964a(8) =15502a(9) =48103a(10) =148490a(11) =456416a(12) =1397905a(13) =4268740a(14) =13002638a(15) =39522143a(16) =119912698a(17) =363262672a(18) =1099015481a(19) =3321204260a(20) =10026858766a(21) =30246156439a(22) =91171963754a(23) =274650794432a(24) =826923598369