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 A009987 #44 Jul 08 2025 11:28:19 %S A009987 1,43,1849,79507,3418801,147008443,6321363049,271818611107, %T A009987 11688200277601,502592611936843,21611482313284249,929293739471222707, %U A009987 39959630797262576401,1718264124282290785243,73885357344138503765449 %N A009987 Powers of 43. %C A009987 Same as Pisot sequences E(1, 43), L(1, 43), P(1, 43), T(1, 43). Essentially same as Pisot sequences E(43, 1849), L(43, 1849), P(43, 1849), T(43, 1849). See A008776 for definitions of Pisot sequences. %C A009987 The compositions of n in which each natural number is colored by one of p different colors are called p-colored compositions of n. For n>=1, a(n) equals the number of 43-colored compositions of n such that no adjacent parts have the same color. - _Milan Janjic_, Nov 17 2011 %C A009987 Numbers n such that sigma(43*n) = 43*n + sigma(n). - _Jahangeer Kholdi_, Nov 24 2013 %H A009987 T. D. Noe, <a href="/A009987/b009987.txt">Table of n, a(n) for n = 0..100</a> %H A009987 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a> %H A009987 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (43). %F A009987 G.f.: 1/(1-43*x). - _Philippe Deléham_, Nov 24 2008 %F A009987 a(n) = 43^n; a(n) = 43*a(n-1), a(0)=1. - _Vincenzo Librandi_, Nov 21 2010 %t A009987 43^Range[0,20] (* _Harvey P. Dale_, Nov 30 2014 *) %o A009987 (Magma)[43^n: n in [0..20]]; // _Vincenzo Librandi_, Nov 21 2010 %o A009987 (PARI) a(n)=43^n \\ _Charles R Greathouse IV_, Oct 07 2015 %K A009987 nonn,easy %O A009987 0,2 %A A009987 _N. J. A. Sloane_