a(0) = 0; a(n) = 5*a(n-1) + 5.

Terms

a(0) =0a(1) =5a(2) =30a(3) =155a(4) =780a(5) =3905a(6) =19530a(7) =97655a(8) =488280a(9) =2441405a(10) =12207030a(11) =61035155a(12) =305175780a(13) =1525878905a(14) =7629394530a(15) =38146972655a(16) =190734863280a(17) =953674316405