Partial sums of A014825, second partial sums of A002450.

Terms

a(0) =1a(1) =7a(2) =34a(3) =146a(4) =599a(5) =2417a(6) =9696a(7) =38820a(8) =155325a(9) =621355a(10) =2485486a(11) =9942022a(12) =39768179a(13) =159072821a(14) =636291404a(15) =2545165752a(16) =10180663161a(17) =40722652815a(18) =162890611450a(19) =651562446010