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 A022270 #37 Sep 08 2022 08:44:46
%S A022270 0,6,25,57,102,160,231,315,412,522,645,781,930,1092,1267,1455,1656,
%T A022270 1870,2097,2337,2590,2856,3135,3427,3732,4050,4381,4725,5082,5452,
%U A022270 5835,6231,6640,7062,7497,7945,8406,8880,9367,9867,10380,10906,11445
%N A022270 a(n) = n*(13*n - 1)/2.
%H A022270 G. C. Greubel, <a href="/A022270/b022270.txt">Table of n, a(n) for n = 0..5000</a>
%H A022270 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A022270 a(n) = 13*n + a(n-1) - 7 for n>0, a(0)=0. - _Vincenzo Librandi_, Aug 04 2010
%F A022270 a(0)=0, a(1)=6, a(2)=25; for n>2, a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - _Harvey P. Dale_, Dec 02 2011
%F A022270 G.f.: x*(6 + 7*x)/(1 - x)^3. - _Vincenzo Librandi_, Mar 31 2015
%F A022270 a(n) = A022271(-n). - _Bruno Berselli_, Mar 31 2015
%F A022270 a(n) = A000217(7*n-1) - A000217(6*n-1). - _Bruno Berselli_, Oct 17 2016
%F A022270 E.g.f.: (x/2)*(13*x + 12)*exp(x). - _G. C. Greubel_, Aug 23 2017
%t A022270 Table[n (13 n - 1)/2, {n, 0, 40}] (* or *) LinearRecurrence[{3,-3,1},{0,6,25},40] (* _Harvey P. Dale_, Dec 02 2011 *)
%t A022270 CoefficientList[Series[x (6 + 7 x) / (1 - x)^3, {x, 0, 40}], x] (* _Vincenzo Librandi_, Mar 31 2015 *)
%o A022270 (PARI) A022270(n) = n*(13*n-1)/2 \\ _Michael B. Porter_, Mar 12 2010
%o A022270 (Magma) [n*(13*n - 1)/2: n in [0..45]]; // _Vincenzo Librandi_, Mar 31 2015
%Y A022270 Cf. A000217, A022271.
%Y A022270 Cf. similar sequences listed in A022288.
%K A022270 nonn,easy
%O A022270 0,2
%A A022270 _N. J. A. Sloane_
%E A022270 More terms from _Vincenzo Librandi_, Mar 31 2015