a(n) = 3*a(n-1) - a(n-2) + 8 with a(0)=1, a(1)=11.

Terms

a(0) =1a(1) =11a(2) =40a(3) =117a(4) =319a(5) =848a(6) =2233a(7) =5859a(8) =15352a(9) =40205a(10) =105271a(11) =275616a(12) =721585a(13) =1889147a(14) =4945864a(15) =12948453a(16) =33899503a(17) =88750064a(18) =232350697a(19) =608302035a(20) =1592555416a(21) =4169364221a(22) =10915537255a(23) =28577247552a(24) =74816205409