Partial sums of A005165.

Terms

a(0) =0a(1) =1a(2) =2a(3) =7a(4) =26a(5) =127a(6) =746a(7) =5167a(8) =41066a(9) =368047a(10) =3669866a(11) =40284847a(12) =482671466a(13) =6267305647a(14) =87660962666