Number of base 9 n-digit numbers with adjacent digits differing by one or less.

Terms

a(0) =1a(1) =9a(2) =25a(3) =71a(4) =203a(5) =583a(6) =1679a(7) =4845a(8) =14001a(9) =40503a(10) =117263a(11) =339699a(12) =984515a(13) =2854281a(14) =8277153a(15) =24007543a(16) =69642819a(17) =202046535a(18) =586220911a(19) =1700972653a(20) =4935747673a(21) =14322646039a(22) =41562779655a(23) =120613013891a(24) =350017652003