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 A016840 #14 Aug 25 2025 09:12:34
%S A016840 81,2401,14641,50625,130321,279841,531441,923521,1500625,2313441,
%T A016840 3418801,4879681,6765201,9150625,12117361,15752961,20151121,25411681,
%U A016840 31640625,38950081,47458321,57289761
%N A016840 a(n) = (4*n+3)^4.
%H A016840 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5,-10,10,-5,1).
%F A016840 a(n) = 5*a(n-1)- 10*a(n-2)+10*a(n-3)-5*a(n-4)+a(n-5). - _Harvey P. Dale_, Dec 08 2011
%t A016840 (4*Range[0,30]+3)^4 (* or *) LinearRecurrence[{5,-10,10,-5,1},{81,2401,14641,50625,130321},30] (* _Harvey P. Dale_, Dec 08 2011 *)
%K A016840 nonn,easy,changed
%O A016840 0,1
%A A016840 _N. J. A. Sloane_