a(0) = a(1) = 1; for n > 1, a(n) = (n+2)*2^(n-2).

Terms

a(0) =1a(1) =1a(2) =4a(3) =10a(4) =24a(5) =56a(6) =128a(7) =288a(8) =640a(9) =1408a(10) =3072a(11) =6656a(12) =14336a(13) =30720a(14) =65536a(15) =139264a(16) =294912a(17) =622592a(18) =1310720a(19) =2752512a(20) =5767168a(21) =12058624a(22) =25165824a(23) =52428800a(24) =109051904a(25) =226492416a(26) =469762048a(27) =973078528a(28) =2013265920a(29) =4160749568