a(n) = 2*a(n-1) + 5*a(n-2), with a(0) = a(1) = 1.

Terms

a(0) =1a(1) =1a(2) =7a(3) =19a(4) =73a(5) =241a(6) =847a(7) =2899a(8) =10033a(9) =34561a(10) =119287a(11) =411379a(12) =1419193a(13) =4895281a(14) =16886527a(15) =58249459a(16) =200931553a(17) =693110401a(18) =2390878567a(19) =8247309139a(20) =28449011113a(21) =98134567921a(22) =338514191407