a(n) = 4*a(n-1) + 3*a(n-2) - 14*a(n-3) + 8*a(n-4).

Terms

a(0) =0a(1) =1a(2) =2a(3) =11a(4) =36a(5) =157a(6) =598a(7) =2447a(8) =9672a(9) =38913a(10) =155194a(11) =621683a(12) =2484908a(13) =9943269a(14) =39765790a(15) =159077719a(16) =636281744a(17) =2545185225a(18) =10180624386a(19) =40722730555a(20) =162890456180a(21) =651562756781