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

Terms

a(0) =1a(1) =7a(2) =35a(3) =155a(4) =651a(5) =2667a(6) =10795a(7) =43435a(8) =174251a(9) =698027a(10) =2794155a(11) =11180715a(12) =44731051a(13) =178940587a(14) =715795115a(15) =2863245995a(16) =11453115051a(17) =45812722347a(18) =183251413675a(19) =733006703275