a(n) = 8*a(n-2), with a(0) = 7, a(1) = 14.

Terms

a(0) =7a(1) =14a(2) =56a(3) =112a(4) =448a(5) =896a(6) =3584a(7) =7168a(8) =28672a(9) =57344a(10) =229376a(11) =458752a(12) =1835008a(13) =3670016a(14) =14680064a(15) =29360128a(16) =117440512a(17) =234881024a(18) =939524096a(19) =1879048192a(20) =7516192768a(21) =15032385536a(22) =60129542144a(23) =120259084288a(24) =481036337152