a(n) = 5*a(n-1) - a(n-2) for n > 1, a(0) = 0, a(1) = 1.

Terms

a(0) =0a(1) =1a(2) =5a(3) =24a(4) =115a(5) =551a(6) =2640a(7) =12649a(8) =60605a(9) =290376a(10) =1391275a(11) =6665999a(12) =31938720a(13) =153027601a(14) =733199285a(15) =3512968824a(16) =16831644835a(17) =80645255351a(18) =386394631920