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 A124947 #12 Apr 30 2025 14:49:06
%S A124947 1,19,89,331,1437,6289,28241,128413,590197,2734297,12749679,59763613,
%T A124947 281370909,1329632401,6303226767,29963180101,142776168261,
%U A124947 681776377177,3261689820791,15630400760077,75015245736567,360509440244557
%N A124947 Number of base 19 circular n-digit numbers with adjacent digits differing by 2 or less.
%C A124947 [Empirical] a(base,n)=a(base-1,n)+A005191(n+1) for base>=2.int(n/2)+1.
%C A124947 See A285280 for confirmation of linear recurrence and code to produce sequence. - _Ray Chandler_, Aug 12 2023.
%H A124947 Ray Chandler, <a href="/A124947/b124947.txt">Table of n, a(n) for n = 0..99</a>
%H A124947 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 A124947 <a href="/index/Rec#order_18">Index entries for linear recurrences with constant coefficients</a>, signature (19, -136, 408, -125, -1987, 3002, 3146, -8052, -1870, 9565, -23, -5762, 442, 1720, -150, -220, 16, 8).
%o A124947 (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 A124947 Cf. Row 19 of A285280.
%K A124947 nonn,base
%O A124947 0,2
%A A124947 _R. H. Hardin_, Dec 28 2006