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 A257288 #14 Nov 17 2023 21:44:49
%S A257288 1,14,154,1526,14266,128534,1129114,9738806,82851706,697402454,
%T A257288 5821341274,48265581686,397988613946,3266956634774,26716987140634,
%U A257288 217805235562166,1770927253556986,14366815611873494,116330307978911194,940412945418752246,7591696934462256826
%N A257288 a(n) = 7*8^n-6*7^n.
%C A257288 First differences of 8^n-7^n = A016177.
%C A257288 a(n-1) is the number of numbers with n digits having the largest digit equal to 7. Note that this is independent of the base b > 7.
%C A257288 Equivalently, number of n-letter words over a 8-letter alphabet, which must not start with the last letter of the alphabet, and in which the first letter of the alphabet must appear.
%H A257288 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (15,-56).
%F A257288 G.f.: (1-x)/((1-7*x)*(1-8*x)). - _Vincenzo Librandi_, May 04 2015
%F A257288 E.g.f.: exp(7*x)*(7*exp(x) - 6). - _Stefano Spezia_, Nov 15 2023
%t A257288 Table[7 8^n - 6 7^n, {n, 0, 30}] (* _Vincenzo Librandi_, May 04 2015 *)
%o A257288 (PARI) a(n)=7*8^n-6*7^n
%o A257288 (Magma) [7*8^n-6*7^n: n in [0..20]]; // _Vincenzo Librandi_, May 04 2015
%Y A257288 Cf. A016177.
%K A257288 nonn,easy
%O A257288 0,2
%A A257288 _M. F. Hasler_, May 03 2015