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 A125357 #9 Apr 30 2025 15:14:25
%S A125357 1,20,160,1040,7880,60720,479296,3835544,31025864,253006376,
%T A125357 2076361620,17126818652,141850168856,1178779027316,9822495145882,
%U A125357 82032520847910,686360207228280,5751457669257720,48255474860875126,405286028562477798
%N A125357 Number of base 20 circular n-digit numbers with adjacent digits differing by 4 or less.
%C A125357 [Empirical] a(base,n)=a(base-1,n)+A025014(n+1) for base>=4.int(n/2)+1
%H A125357 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 A125357 (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>4)+($[(i+1)mod N]`-$[i]`>4))
%K A125357 nonn,base
%O A125357 0,2
%A A125357 _R. H. Hardin_, Dec 28 2006