a(n) = ((2^n*n + i*(1 - i)^n - i*(1 + i)^n))/4, where i is the imaginary unit.

Terms

a(0) =0a(1) =1a(2) =3a(3) =7a(4) =16a(5) =38a(6) =92a(7) =220a(8) =512a(9) =1160a(10) =2576a(11) =5648a(12) =12288a(13) =26592a(14) =57280a(15) =122816a(16) =262144a(17) =557184a(18) =1179904a(19) =2490624a(20) =5242880a(21) =11009536a(22) =23067648a(23) =48233472a(24) =100663296a(25) =209717248a(26) =436211712a(27) =905973760a(28) =1879048192a(29) =3892305920