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 A257286 #23 Nov 15 2023 19:05:15
%S A257286 1,10,80,580,3980,26380,170780,1087180,6835580,42575980,263268380,
%T A257286 1618672780,9907349180,60420657580,367406757980,2228854610380,
%U A257286 13495197974780,81581539411180,492540994279580,2970504754739980,17899322473752380
%N A257286 a(n) = 5*6^n - 4*5^n.
%C A257286 First differences of 6^n - 5^n = A005062.
%C A257286 a(n-1) is the number of numbers with n digits having the largest digit equal to 5. Or, equivalently, number of n-letter words over a 6-letter alphabet {a,b,c,d,e,f}, which must not start with the first letter of the alphabet, and in which the last letter of the alphabet must appear.
%H A257286 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-30).
%F A257286 a(n) = 11 a(n-1) - 30 a(n-2).
%F A257286 G.f.: (1-x)/((1-5*x)*(1-6*x)). - _Vincenzo Librandi_, May 04 2015
%F A257286 E.g.f.: exp(5*x)*(5*exp(x) - 4). - _Stefano Spezia_, Nov 15 2023
%t A257286 Table[5 6^n - 4 5^n, {n, 0, 30}] (* _Vincenzo Librandi_, May 04 2015 *)
%o A257286 (PARI) a(n)=5*6^n-4*5^n
%o A257286 (Magma) [5*6^n-4*5^n: n in [0..20]]; // _Vincenzo Librandi_, May 04 2015
%Y A257286 Cf. A005062.
%Y A257286 Coincides with A125373 only for the first terms.
%Y A257286 See also A000225, A027649, A255463, A257285, A257286, A257287, A257288, A257289 and A088924.
%K A257286 nonn,easy
%O A257286 0,2
%A A257286 _M. F. Hasler_, May 03 2015