a(n) = A359720(n+3,2), for n >= 0.

Terms

a(0) =1a(1) =9a(2) =49a(3) =179a(4) =711a(5) =2390a(6) =8361a(7) =27082a(8) =89389a(9) =283170a(10) =905307a(11) =2825245a(12) =8854116a(13) =27341969a(14) =84550769a(15) =259046260a(16) =793589833a(17) =2416512240a(18) =7352490113a(19) =22279068811a(20) =67435591018a(21) =203525629398a(22) =613550161717