a(n) = A306912(n) - 2.

Terms

a(0) =0a(1) =1a(2) =3a(3) =6a(4) =12a(5) =19a(6) =33a(7) =50a(8) =77a(9) =111a(10) =166a(11) =229a(12) =329a(13) =448a(14) =615a(15) =824a(16) =1120a(17) =1467a(18) =1956a(19) =2538a(20) =3313a(21) =4258a(22) =5512a(23) =6993a(24) =8944a(25) =11278a(26) =14258a(27) =17838a(28) =22402a(29) =27788