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 A013756 #24 Sep 06 2023 14:34:07
%S A013756 15,50625,170859375,576650390625,1946195068359375,6568408355712890625,
%T A013756 22168378200531005859375,74818276426792144775390625,
%U A013756 252511682940423488616943359375,852226929923929274082183837890625,2876265888493261300027370452880859375
%N A013756 a(n) = 15^(3*n + 1).
%H A013756 Vincenzo Librandi, <a href="/A013756/b013756.txt">Table of n, a(n) for n = 0..200</a>
%H A013756 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H A013756 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (3375).
%F A013756 From _Philippe Deléham_, Dec 03 2008: (Start)
%F A013756 a(n) = 3375*a(n-1); a(0)=15
%F A013756 G.f.: 15/(1-3375*x). (End)
%t A013756 Table[15^(3n+1),{n,0,10}] (* or *) NestList[3375#&,15,10] (* _Harvey P. Dale_, Sep 06 2023 *)
%o A013756 (Magma) [15^(3*n+1): n in [0..15]]; // _Vincenzo Librandi_, Jun 27 2011
%o A013756 (PARI) a(n)=15^(3*n+1) \\ _Charles R Greathouse IV_, Jul 10 2016
%Y A013756 Subsequence of A001024.
%K A013756 nonn,easy
%O A013756 0,1
%A A013756 _N. J. A. Sloane_