a(n) = binomial(n+6, 6)*5^n.

Terms

a(0) =1a(1) =35a(2) =700a(3) =10500a(4) =131250a(5) =1443750a(6) =14437500a(7) =134062500a(8) =1173046875a(9) =9775390625a(10) =78203125000a(11) =604296875000