a(n) = 6*a(n-1) - 8*a(n-2) for n > 1; a(0) = 7, a(1) = 30.

Terms

a(0) =7a(1) =30a(2) =124a(3) =504a(4) =2032a(5) =8160a(6) =32704a(7) =130944a(8) =524032a(9) =2096640a(10) =8387584a(11) =33552384a(12) =134213632a(13) =536862720a(14) =2147467264a(15) =8589901824a(16) =34359672832a(17) =137438822400a(18) =549755551744