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 A016874 #34 Feb 16 2025 08:32:33
%S A016874 4,49,144,289,484,729,1024,1369,1764,2209,2704,3249,3844,4489,5184,
%T A016874 5929,6724,7569,8464,9409,10404,11449,12544,13689,14884,16129,17424,
%U A016874 18769,20164,21609,23104,24649,26244
%N A016874 a(n) = (5*n + 2)^2.
%H A016874 Vincenzo Librandi, <a href="/A016874/b016874.txt">Table of n, a(n) for n = 0..2000</a>
%H A016874 Eric Weisstein's MathWorld, <a href="https://mathworld.wolfram.com/PolygammaFunction.html">Polygamma Function</a>.
%H A016874 Wikipedia, <a href="http://en.wikipedia.org/wiki/Polygamma_function">Polygamma Function</a>.
%H A016874 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A016874 a(n) = a(n-1) + 50*n - 5; a(0)=4. - _Vincenzo Librandi_, Jun 07 2011
%F A016874 Sum_{n>=0} 1/a(n) = polygamma(1, 2/5)/25 = 0.2910142636... - _Amiram Eldar_, Oct 02 2020
%F A016874 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - _Wesley Ivan Hurt_, Oct 02 2020
%F A016874 G.f.: -(4+x)*(1+9*x)/(-1+x)^3. - _Wesley Ivan Hurt_, Oct 02 2020
%e A016874 a(0) = (5*0 + 2)^2 = 4.
%t A016874 (5*Range[0,40]+2)^2 (* _Harvey P. Dale_, Feb 19 2011 *)
%o A016874 (Magma) [(5*n+2)^2: n in [0..40]]; // _Vincenzo Librandi_, Jun 07 2011
%o A016874 (PARI) a(n)=(5*n+2)^2 \\ _Charles R Greathouse IV_, Jun 17 2017
%K A016874 nonn,easy
%O A016874 0,1
%A A016874 _N. J. A. Sloane_