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 A124718 #12 Apr 30 2025 14:01:32
%S A124718 1,25,73,169,453,1205,3301,9125,25501,71773,203253,578405,1652793,
%T A124718 4739305,13630417,39303329,113588941,328938125,954262789,2772787445,
%U A124718 8068471393,23508942353,68578993897,200272341785,585441977665
%N A124718 Number of base 25 circular n-digit numbers with adjacent digits differing by 1 or less.
%C A124718 [Empirical] a(base,n)=a(base-1,n)+A002426(n+1) for base>=1.int(n/2)+1
%C A124718 a(n) = T(n, 25) where T(n, k) = Sum_{j=1..k} (1+2*cos(j*Pi/(k+1)))^n. These are the number of smooth cyclic words of length n over the alphabet {1,2,..,25}. See theorem 3.3 in Knopfmacher and others, reference in A124696. - _Peter Luschny_, Aug 13 2012
%H A124718 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>
%o A124718 (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>1)+($[(i+1)mod N]`-$[i]`>1))
%K A124718 nonn,base
%O A124718 0,2
%A A124718 _R. H. Hardin_, Dec 28 2006