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

Terms

a(0) =0a(1) =9a(2) =94a(3) =719a(4) =4844a(5) =30469a(6) =183594a(7) =1074219a(8) =6152344a(9) =34667969a(10) =192871094a(11) =1062011719a(12) =5798339844a(13) =31433105469a(14) =169372558594a(15) =907897949219