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%I #10 Aug 12 2023 11:01:06
%S 1,18,84,312,1352,5908,26490,120278,552032,2553972,11892734,55672118,
%T 261759734,1235323302,5848421012,27764530552,132124679472,
%U 630077734772,3010344270942,14406602755262,69048608938842,331383832210022
%N Number of base 18 circular n-digit numbers with adjacent digits differing by 2 or less.
%C [Empirical] a(base,n)=a(base-1,n)+A005191(n+1) for base>=2.int(n/2)+1.
%C See A285280 for confirmation of linear recurrence and code to produce sequence. - _Ray Chandler_, Aug 12 2023.
%H Ray Chandler, <a href="/A124935/b124935.txt">Table of n, a(n) for n = 0..99</a>
%H <a href="/index/Rec#order_16">Index entries for linear recurrences with constant coefficients</a>, signature (18, -120, 320, 14, -1624, 1767, 2860, -4610, -2408, 4913, 1016, -2500, -200, 580, 16, -48).
%o (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>2)+($[(i+1)mod N]`-$[i]`>2))
%Y Cf. Row 18 of A285280.
%K nonn,base
%O 0,2
%A _R. H. Hardin_, Dec 28 2006
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