a(n) is the difference between A084321(n) and the (n-1)th power of 2.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =3a(5) =3a(6) =0a(7) =11a(8) =0a(9) =24a(10) =37a(11) =47a(12) =73a(13) =90a(14) =133a(15) =135a(16) =110a(17) =133a(18) =435a(19) =795a(20) =317a(21) =1674a(22) =1217a(23) =1975a(24) =4816a(25) =6177a(26) =9483a(27) =11885a(28) =17724a(29) =19562