a(n) = Sum_{k=1..n} 2^k * tau(k), where tau(k) = A000005(k).

Terms

a(0) =2a(1) =10a(2) =26a(3) =74a(4) =138a(5) =394a(6) =650a(7) =1674a(8) =3210a(9) =7306a(10) =11402a(11) =35978a(12) =52362a(13) =117898a(14) =248970a(15) =576650a(16) =838794a(17) =2411658a(18) =3460234a(19) =9751690a(20) =18140298a(21) =34917514a(22) =51694730a(23) =185912458a(24) =286575754a(25) =555011210a(26) =1091882122a(27) =2702494858a(28) =3776236682a(29) =12366171274