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

Terms

a(0) =1a(1) =5a(2) =15a(3) =55a(4) =185a(5) =645a(6) =2215a(7) =7655a(8) =26385a(9) =91045a(10) =314015a(11) =1083255a(12) =3736585a(13) =12889445a(14) =44461815a(15) =153370855a(16) =529050785a(17) =1824955845a(18) =6295165615a(19) =21715110455a(20) =74906048985a(21) =258387650245a(22) =891305545415