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 A027475 #37 Sep 08 2022 08:44:49
%S A027475 1,30,675,13500,253125,4556250,79734375,1366875000,23066015625,
%T A027475 384433593750,6343154296875,103797070312500,1686702392578125,
%U A027475 27246730957031250,437893890380859375,7006302246093750000
%N A027475 a(n) = (n-1) * 15^(n-2).
%C A027475 Second column of A027467.
%H A027475 Vincenzo Librandi, <a href="/A027475/b027475.txt">Table of n, a(n) for n = 2..200</a>
%H A027475 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (30,-225).
%F A027475 Numerators of sequence a[2,n] in (a[i,j])^4 where a[i,j] = binomial(i-1, j-1)/2^(i-1) if j<=i, 0 if j>i.
%F A027475 G.f.: x^2/(1 - 15*x)^2. - _Vincenzo Librandi_, Jul 16 2018
%F A027475 a(2) = 1, a(3) = 30; for n >= 4, a(n) = 30*a(n-1) - 225*a(n-2). - _Jianing Song_, Jul 16 2018
%p A027475 seq((n-1)*15^(n-2), n=2..50); # _Muniru A Asiru_, Jul 15 2018
%t A027475 a[n_]:= n 15^(n-1); a[Range[40]] (* _Vladimir Joseph Stephan Orlovsky_, Feb 09 2011 *)
%t A027475 CoefficientList[Series[x^2/(1-15x)^2, {x, 0, 33}], x] (* _Vincenzo Librandi_, Jul 16 2018 *)
%o A027475 (Magma) [(n-1)*15^(n-2): n in [2..50]]; // _Vincenzo Librandi_, Dec 29 2012
%o A027475 (GAP) List([2..50],n->(n-1)*15^(n-2)); # _Muniru A Asiru_, Jul 15 2018
%o A027475 (Sage) [15^(n-2)*(n-1) for n in (2..50)] # _G. C. Greubel_, May 14 2021
%Y A027475 Cf. A027467.
%K A027475 nonn,easy
%O A027475 2,2
%A A027475 _Olivier Gérard_
%E A027475 More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 17 2005