a(n) = A046161(n) + A001803(n).

Terms

a(0) =2a(1) =5a(2) =23a(3) =51a(4) =443a(5) =949a(6) =4027a(7) =8483a(8) =142163a(9) =296481a(10) =1232113a(11) =2552405a(12) =21095279a(13) =43490633a(14) =178977107a(15) =367649059a(16) =12065310083a(17) =24714021721a(18) =101124870709a(19) =206667899393