a(n) = 4^n + 10*2^n + 4*3^n + 20.

Terms

a(0) =35a(1) =56a(2) =112a(3) =272a(4) =760a(5) =2336a(6) =7672a(7) =26432a(8) =94360a(9) =346016a(10) =1295032a(11) =4923392a(12) =18943960a(13) =73568096a(14) =287731192a(15) =1131465152a(16) =4467809560a(17) =17697740576a(18) =70271780152a(19) =279532195712