a(n) = floor(n*2^n/(n + 1)).

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =12a(5) =26a(6) =54a(7) =112a(8) =227a(9) =460a(10) =930a(11) =1877a(12) =3780a(13) =7606a(14) =15291a(15) =30720a(16) =61680a(17) =123790a(18) =248346a(19) =498073a(20) =998643a(21) =2001826a(22) =4011942a(23) =8039082a(24) =16106127a(25) =32263876a(26) =64623350a(27) =129424237a(28) =259179060a(29) =518975214