Number of empty faces in Freij's family of Hansen polytopes.

Terms

a(0) =17a(1) =19a(2) =25a(3) =43a(4) =97a(5) =259a(6) =745a(7) =2203a(8) =6577a(9) =19699a(10) =59065a(11) =177163a(12) =531457a(13) =1594339a(14) =4782985a(15) =14348923a(16) =43046737a(17) =129140179a(18) =387420505a(19) =1162261483a(20) =3486784417a(21) =10460353219a(22) =31381059625a(23) =94143178843a(24) =282429536497a(25) =847288609459