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 A124958 #12 Apr 30 2025 14:53:58
%S A124958 1,30,144,540,2372,10480,47502,217898,1010012,4717872,22176074,
%T A124958 104770058,497093834,2367032490,11306090072,54148325140,259942544940,
%U A124958 1250461443632,6026490869130,29092178813042,140648250533742
%N A124958 Number of base 30 circular n-digit numbers with adjacent digits differing by 2 or less.
%C A124958 [Empirical] a(base,n)=a(base-1,n)+A005191(n+1) for base>=2.int(n/2)+1.
%C A124958 See A285280 for confirmation of linear recurrence and code to produce sequence. - _Ray Chandler_, Aug 12 2023.
%H A124958 Ray Chandler, <a href="/A124958/b124958.txt">Table of n, a(n) for n = 0..99</a>
%H A124958 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 A124958 <a href="/index/Rec#order_30">Index entries for linear recurrences with constant coefficients</a>, signature (30, -378, 2520, -8749, 8606, 45099, -155848, 38225, 588434, -724872, -1035936, 2242113, 860030, -3676846, -59744, 3730019, -548938, -2444170, 531256, 1034263, -243602, -273783, 60600, 42329, -7854, -3360, 448, 105, -6, -1).
%o A124958 (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 A124958 Cf. Row 30 of A285280.
%K A124958 nonn,base
%O A124958 0,2
%A A124958 _R. H. Hardin_, Dec 28 2006