a(n) = 5*a(n-1) - a(n-2) + 1 with a(0)=1, a(1)=6.

Terms

a(0) =1a(1) =6a(2) =30a(3) =145a(4) =696a(5) =3336a(6) =15985a(7) =76590a(8) =366966a(9) =1758241a(10) =8424240a(11) =40362960a(12) =193390561a(13) =926589846a(14) =4439558670a(15) =21271203505a(16) =101916458856a(17) =488311090776