a(n) = sum{k=0 to n} A139021(k).

Terms

a(0) =2a(1) =5a(2) =16a(3) =29a(4) =256a(5) =563a(6) =1024a(7) =1487a(8) =4096a(9) =6779a(10) =65536a(11) =124367a(12) =262144a(13) =400151a(14) =17179869184a(15) =34359339617a(16) =274877906944a(17) =515396474423