This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A124828 #17 Apr 30 2025 14:33:07
%S A124828 1,7,29,103,417,1717,7229,30793,132225,570649,2470769,10719793,
%T A124828 46569777,202477633,880792193,3832748833,16681516545,72613292353,
%U A124828 316105114817,1376159456641,5991281182977,26084303730049
%N A124828 Number of base 7 circular n-digit numbers with adjacent digits differing by 2 or less.
%C A124828 [Empirical] a(base,n)=a(base-1,n)+A005191(n+1) for base>=2.int(n/2)+1.
%C A124828 See A285280 for confirmation of linear recurrence and code to produce sequence; also confirms conjectured g.f. from _Colin Barker_. - _Ray Chandler_, Aug 12 2023.
%H A124828 Ray Chandler, <a href="/A124828/b124828.txt">Table of n, a(n) for n = 0..99</a>
%H A124828 OEIS Wiki, <a href="/wiki/Number_of_base_k_circular_n-digit_numbers_with_adjacent_digits_differing_by_d_or_less">Number of base k circular n-digit numbers with adjacent digits differing by d or less</a>
%H A124828 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (7, -10, -10, 14, 4, -4).
%F A124828 G.f.: (1 - 10*x^2 - 20*x^3 + 42*x^4 + 16*x^5 - 20*x^6) / ((1 - x)*(1 - 2*x - 2*x^2)*(1 - 4*x - 2*x^2 + 2*x^3)). - _Colin Barker_, Jun 03 2017
%o A124828 (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 A124828 Cf. Row 7 of A285280.
%K A124828 nonn,base
%O A124828 0,2
%A A124828 _R. H. Hardin_, Dec 28 2006