%I #8 Jul 18 2017 08:01:22
%S 1,16,74,350,1668,7986,38348,184524,889230,4290030,20714382,100083072,
%T 483793208,2339478320,11316186924,54748710158,264922095330,
%U 1282082867386,6205185792886,30034782040334,145384379570694
%N Number of base 16 n-digit numbers with adjacent digits differing by two or less.
%C [Empirical] a(base,n)=a(base-1,n)+5^(n-1) for base>=2n-1; a(base,n)=a(base-1,n)+5^(n-1)-2 when base=2n-2.
%F G.f.: (1+7*x-51*x^2+4*x^3+131*x^4+10*x^5-61*x^6-2*x^7+3*x^8) / (1-9*x+19*x^2+16*x^3-49*x^4-14*x^5+23*x^6+2*x^7-x^8) (conjectured). - _Colin Barker_, Jul 18 2017
%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>2)+($[i+1]`-$[i]`>2))
%Y Cf. Base 16 differing by one or less A126370.
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006
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