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 A125330 #9 Apr 30 2025 15:05:07
%S A125330 1,20,128,656,3928,23840,148304,934968,5958552,38285216,247607348,
%T A125330 1609914524,10513615792,68913452056,453123210178,2987405569166,
%U A125330 19741419610536,130718419293680,867078544410362,5760352822741182
%N A125330 Number of base 20 circular n-digit numbers with adjacent digits differing by 3 or less.
%C A125330 [Empirical] a(base,n)=a(base-1,n)+A025012(n+1) for base>=3.int(n/2)+1
%H A125330 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 A125330 (S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-1](($[i]`-$[(i+1)mod N]`>3)+($[(i+1)mod N]`-$[i]`>3))
%K A125330 nonn,base
%O A125330 0,2
%A A125330 _R. H. Hardin_, Dec 28 2006