a(n) = n*(n + ceiling(2^n/12)).

Terms

a(0) =0a(1) =2a(2) =6a(3) =12a(4) =24a(5) =40a(6) =72a(7) =126a(8) =240a(9) =468a(10) =960a(11) =2002a(12) =4248a(13) =9048a(14) =19320a(15) =41190a(16) =87648a(17) =185980a(18) =393552a(19) =830490a(20) =1748040a(21) =3670464a(22) =7690056a(23) =16078702a(24) =33555024a(25) =69905700a(26) =145403232a(27) =301990626a(28) =626350200a(29) =1297438888