a(n) = 5*a(n-1) + 10*a(n-2).

Terms

a(0) =1a(1) =15a(2) =85a(3) =575a(4) =3725a(5) =24375a(6) =159125a(7) =1039375a(8) =6788125a(9) =44334375a(10) =289553125a(11) =1891109375a(12) =12351078125a(13) =80666484375a(14) =526843203125