A126487 - OEIS

%I #9 Jul 18 2017 12:26:00

%S 1,19,121,791,5217,34587,230033,1533159,10233063,68367029,457062389,

%T 3057032825,20453043685,136869404619,916044100681,6131521065627,

%U 41043887722493,274756556545945,1839334652522085,12313523619477007

%N Number of base 19 n-digit numbers with adjacent digits differing by three or less.

%C [Empirical] a(base,n)=a(base-1,n)+7^(n-1) for base>=3n-2; a(base,n)=a(base-1,n)+7^(n-1)-2 when base=3n-3.

%F G.f.: (1+8*x-64*x^2-36*x^3+236*x^4+91*x^5-231*x^6-80*x^7+63*x^8+18*x^9) / (1-11*x+24*x^2+48*x^3-96*x^4-77*x^5+96*x^6+49*x^7-27*x^8-9*x^9) (conjectured). - _Colin Barker_, Jul 18 2017

%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>3)+($[i+1]`-$[i]`>3))

%Y Cf. Base 19 differing by two or less A126406, one or less A126373.

%K nonn,base

%O 0,2

%A _R. H. Hardin_, Dec 27 2006