a(n) = 5*(3*6^n + 2^n)/2.

Terms

a(0) =10a(1) =50a(2) =280a(3) =1640a(4) =9760a(5) =58400a(6) =350080a(7) =2099840a(8) =12597760a(9) =75584000a(10) =453498880a(11) =2720983040a(12) =16325877760a(13) =97955225600a(14) =587731271680