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A126363
Number of base 9 n-digit numbers with adjacent digits differing by one or less.
4
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
0,2
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]
PROG
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>1)+($[i+1]`-$[i]`>1))
CROSSREFS
Sequence in context: A146589 A146866 A271731 * A036836 A125997 A199111
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 26 2006
STATUS
approved