a(n) = 2*a(n-1) + 7*a(n-2) for n > 1; a(0) = 1, a(1) = 13.

Terms

a(0) =1a(1) =13a(2) =33a(3) =157a(4) =545a(5) =2189a(6) =8193a(7) =31709a(8) =120769a(9) =463501a(10) =1772385a(11) =6789277a(12) =25985249a(13) =99495437a(14) =380887617a(15) =1458243293a(16) =5582699905a(17) =21373102861a(18) =81825105057a(19) =313261930141