a(0) = 1, a(n+1) = 2*a(n) + periodic sequence of length 2: repeat [5, -4].

Terms

a(0) =1a(1) =7a(2) =10a(3) =25a(4) =46a(5) =97a(6) =190a(7) =385a(8) =766a(9) =1537a(10) =3070a(11) =6145a(12) =12286a(13) =24577a(14) =49150a(15) =98305a(16) =196606a(17) =393217a(18) =786430a(19) =1572865a(20) =3145726a(21) =6291457a(22) =12582910a(23) =25165825a(24) =50331646a(25) =100663297a(26) =201326590a(27) =402653185a(28) =805306366a(29) =1610612737