A126363 Number of base 9 n-digit numbers with adjacent digits differing by one or less.

1, 9, 25, 71, 203, 583, 1679, 4845, 14001, 40503, 117263, 339699, 984515, 2854281, 8277153, 24007543, 69642819, 202046535, 586220911, 1700972653, 4935747673, 14322646039, 41562779655, 120613013891, 350017652003, 1015758270153

Offset: 0

Author

R. H. Hardin, Dec 26 2006

Keywords

• nonn
• base

Comments

[Empirical] a(base,n)=a(base-1,n)+3^(n-1) for base>=n; a(base,n)=a(base-1,n)+3^(n-1)-2 when base=n-1

Formula

Empirical G.f.: -(2*x^5+13*x^4-4*x^3-15*x^2+4*x+1) / ((x-1)*(x^4+6*x^3+x^2-4*x+1)). [Colin Barker, Nov 26 2012]