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 A013724 #24 Sep 08 2022 08:44:38 %S A013724 19,6859,2476099,893871739,322687697779,116490258898219, %T A013724 42052983462257059,15181127029874798299,5480386857784802185939, %U A013724 1978419655660313589123979,714209495693373205673756419 %N A013724 a(n) = 19^(2*n + 1). %H A013724 Vincenzo Librandi, <a href="/A013724/b013724.txt">Table of n, a(n) for n = 0..200</a> %H A013724 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a> %H A013724 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (361). %F A013724 From _Philippe Deléham_, Nov 28 2008: (Start) %F A013724 a(n) = 361*a(n-1); a(0)=19. %F A013724 G.f.: 19/(1-361*x). (End) %p A013724 seq(19^(2*n+1),n=0..10); # _Nathaniel Johnston_, Jun 25 2011 %t A013724 NestList[361#&,19,20] (* _Harvey P. Dale_, Jun 12 2017 *) %o A013724 (Magma) [19^(2*n+1): n in [0..15]]; // _Vincenzo Librandi_, Jun 26 2011 %o A013724 (PARI) a(n)=19^(2*n+1) \\ _Charles R Greathouse IV_, Jul 11 2016 %Y A013724 Bisection of A001029. %Y A013724 Cf. A013708-A013723, A013725-A013729. %K A013724 nonn,easy %O A013724 0,1 %A A013724 _N. J. A. Sloane_