a(n) = 4*a(n-1) - 8*a(n-2) with a(0) = a(1) = 1.

Terms

a(0) =1a(1) =1a(2) =-4a(3) =-24a(4) =-64a(5) =-64a(6) =256a(7) =1536a(8) =4096a(9) =4096a(10) =-16384a(11) =-98304a(12) =-262144a(13) =-262144a(14) =1048576a(15) =6291456a(16) =16777216a(17) =16777216a(18) =-67108864a(19) =-402653184a(20) =-1073741824a(21) =-1073741824a(22) =4294967296a(23) =25769803776a(24) =68719476736a(25) =68719476736a(26) =-274877906944