a(n) = floor((1287/545)^n).

Terms

a(0) =2a(1) =5a(2) =13a(3) =31a(4) =73a(5) =173a(6) =409a(7) =967a(8) =2283a(9) =5392a(10) =12735a(11) =30073a(12) =71017a(13) =167706a(14) =396032a(15) =935217a(16) =2208486a(17) =5215270a(18) =12315692a(19) =29083113a(20) =68678837a(21) =162182870a(22) =382989640a(23) =904417737a(24) =2135753445a(25) =5043513182a(26) =11910094433a(27) =28125305569a(28) =66417005997