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 A016839 #20 Jul 08 2025 05:56:07
%S A016839 27,343,1331,3375,6859,12167,19683,29791,42875,59319,79507,103823,
%T A016839 132651,166375,205379,250047,300763,357911,421875,493039,571787,
%U A016839 658503,753571,857375,970299,1092727,1225043
%N A016839 a(n) = (4*n+3)^3.
%H A016839 Ivan Panchenko, <a href="/A016839/b016839.txt">Table of n, a(n) for n = 0..200</a>
%H A016839 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).
%F A016839 G.f.: ( 27+235*x+121*x^2+x^3 ) / (x-1)^4 . - _R. J. Mathar_, Dec 03 2015
%F A016839 Sum_{n>=0} 1/a(n) = 7*zeta(3)/16 - Pi^3/64. - _Amiram Eldar_, Jun 28 2020
%t A016839 (4*Range[0,30]+3)^3 (* or *) LinearRecurrence[{4,-6,4,-1},{27,343,1331,3375},30] (* _Harvey P. Dale_, Jul 21 2018 *)
%o A016839 (PARI) a(n) = (4*n+3)^3; \\ _Altug Alkan_, Dec 03 2015
%K A016839 nonn,easy
%O A016839 0,1
%A A016839 _N. J. A. Sloane_