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 A125358 #9 Apr 30 2025 15:14:47
%S A125358 1,21,169,1101,8369,64671,511957,4108671,33331889,272616609,
%T A125358 2244091579,18568201871,154285123493,1286408940149,10756655080753,
%U A125358 90159207784161,757192897525073,6369787770505701,53659598197631131,452559057596166759
%N A125358 Number of base 21 circular n-digit numbers with adjacent digits differing by 4 or less.
%C A125358 [Empirical] a(base,n)=a(base-1,n)+A025014(n+1) for base>=4.int(n/2)+1
%H A125358 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 A125358 (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 A125358 nonn,base
%O A125358 0,2
%A A125358 _R. H. Hardin_, Dec 28 2006