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Number of base 15 n-digit numbers with adjacent digits differing by five or less.
0

%I #11 Jul 19 2017 06:25:35

%S 1,15,135,1265,11945,112969,1068723,10111095,95661377,905057497,

%T 8562802623,81013191559,766470702689,7251625683041,68608069306975,

%U 649105094579799,6141222571633425,58102478303643985,549711062520950431

%N Number of base 15 n-digit numbers with adjacent digits differing by five or less.

%C [Empirical] a(base,n)=a(base-1,n)+11^(n-1) for base>=5n-4; a(base,n)=a(base-1,n)+11^(n-1)-2 when base=5n-5.

%F G.f.: (1+5*x-14*x^2-30*x^3+22*x^4+30*x^5-8*x^6-8*x^7) / (1-10*x+x^2+40*x^3-8*x^4-34*x^5+4*x^6+8*x^7) (conjectured). - _Colin Barker_, Jul 19 2017

%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>5)+($[i+1]`-$[i]`>5))

%Y Cf. Base 15 differing by four or less A126510, three or less A126483, two or less A126402, one or less A126369.

%K nonn,base

%O 0,2

%A _R. H. Hardin_, Dec 28 2006