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 A013720 #25 Sep 08 2022 08:44:38 %S A013720 15,3375,759375,170859375,38443359375,8649755859375,1946195068359375, %T A013720 437893890380859375,98526125335693359375,22168378200531005859375, %U A013720 4987885095119476318359375,1122274146401882171630859375 %N A013720 a(n) = 15^(2*n + 1). %H A013720 Vincenzo Librandi, <a href="/A013720/b013720.txt">Table of n, a(n) for n = 0..200</a> %H A013720 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a> %H A013720 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (225). %F A013720 From _Philippe Deléham_, Nov 25 2008: (Start) %F A013720 a(n) = 225*a(n-1), a(0)=15. %F A013720 G.f.: 15/(1-225*x). (End) %p A013720 seq(15^(2*n+1),n=0..11); # _Nathaniel Johnston_, Jun 25 2011 %t A013720 15^(2Range[0,12]+1) (* _Harvey P. Dale_, Feb 09 2011 *) %o A013720 (Magma) [15^(2*n+1): n in [0..15]]; // _Vincenzo Librandi_, Jun 26 2011 %o A013720 (PARI) a(n)=15^(2*n+1) \\ _Charles R Greathouse IV_, Jul 11 2016 %Y A013720 Bisection of A001024 (15^n). %K A013720 nonn,easy %O A013720 0,1 %A A013720 _N. J. A. Sloane_