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 A017246 #19 Sep 08 2022 08:44:42
%S A017246 49,256,625,1156,1849,2704,3721,4900,6241,7744,9409,11236,13225,15376,
%T A017246 17689,20164,22801,25600,28561,31684,34969,38416,42025,45796,49729,
%U A017246 53824,58081,62500,67081,71824
%N A017246 a(n) = (9*n + 7)^2.
%H A017246 Vincenzo Librandi, <a href="/A017246/b017246.txt">Table of n, a(n) for n = 0..10000</a>
%H A017246 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3, -3, 1).
%F A017246 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3); a(0)=49, a(1)=256, a(2)=625. - _Harvey P. Dale_, Apr 24 2016
%F A017246 G.f.: -(49 + 109*x + 4*x^2)/(x-1)^3. - _R. J. Mathar_, Mar 20 2018
%t A017246 (9*Range[0,30]+7)^2 (* or *) LinearRecurrence[{3,-3,1},{49,256,625},30] (* _Harvey P. Dale_, Apr 24 2016 *)
%o A017246 (Magma) [(9*n+7)^2: n in [0..35]]; // _Vincenzo Librandi_, Jul 27 2011
%o A017246 (PARI) a(n)=(9*n+7)^2 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A017246 Cf. A000290 (n^2), A017245 (9*n+7).
%K A017246 nonn,easy
%O A017246 0,1
%A A017246 _N. J. A. Sloane_