a(n) = 192*2^n - 273 (n>=1).

Terms

a(0) =111a(1) =495a(2) =1263a(3) =2799a(4) =5871a(5) =12015a(6) =24303a(7) =48879a(8) =98031a(9) =196335a(10) =392943a(11) =786159a(12) =1572591a(13) =3145455a(14) =6291183a(15) =12582639a(16) =25165551a(17) =50331375a(18) =100663023a(19) =201326319a(20) =402652911a(21) =805306095a(22) =1610612463a(23) =3221225199a(24) =6442450671a(25) =12884901615a(26) =25769803503a(27) =51539607279a(28) =103079214831a(29) =206158429935