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 A153449 #21 Jun 17 2017 03:37:16
%S A153449 0,11,55,132,242,385,561,770,1012,1287,1595,1936,2310,2717,3157,3630,
%T A153449 4136,4675,5247,5852,6490,7161,7865,8602,9372,10175,11011,11880,12782,
%U A153449 13717,14685,15686,16720,17787,18887,20020,21186,22385
%N A153449 11 times pentagonal numbers: 11*n*(3n-1)/2.
%H A153449 Ivan Panchenko, <a href="/A153449/b153449.txt">Table of n, a(n) for n = 0..1000</a>
%H A153449 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A153449 a(n) = (33*n^2 - 11*n)/2 = A000326(n)*11.
%F A153449 a(n) = 33*n + a(n-1) - 22 (with a(0)=0). - _Vincenzo Librandi_, Aug 03 2010
%F A153449 G.f.: 11*x*(1+2*x)/(1-x)^3. - _Colin Barker_, Feb 21 2012
%F A153449 From _G. C. Greubel_, Aug 21 2016: (Start)
%F A153449 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
%F A153449 E.g.f.: (11/2)*x*(2 + 3*x)*exp(x). (End)
%t A153449 Table[11*n*(3n-1)/2, {n,0,25}] (* or *) LinearRecurrence[{3,-3,1},{0,11,55},25] (* _G. C. Greubel_, Aug 21 2016 *)
%o A153449 (PARI) a(n)=11*n*(3*n-1)/2 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A153449 Cf. A000326.
%K A153449 easy,nonn
%O A153449 0,2
%A A153449 _Omar E. Pol_, Dec 26 2008