Partial sums of A006143.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =1a(5) =1a(6) =3a(7) =10a(8) =22a(9) =36a(10) =72a(11) =167a(12) =393a(13) =894a(14) =1950a(15) =4327a(16) =9775