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 A189836 #29 Feb 12 2024 02:28:57
%S A189836 11,12,15,20,27,36,47,60,75,92,111,132,155,180,207,236,267,300,335,
%T A189836 372,411,452,495,540,587,636,687,740,795,852,911,972,1035,1100,1167,
%U A189836 1236,1307,1380,1455,1532,1611,1692,1775,1860,1947
%N A189836 a(n) = n^2 + 11.
%H A189836 G. C. Greubel, <a href="/A189836/b189836.txt">Table of n, a(n) for n = 0..10000</a>
%H A189836 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A189836 From _G. C. Greubel_, Jan 13 2018: (Start)
%F A189836 G.f.: (11 - 21*x + 12*x^2)/(1 - x)^3.
%F A189836 E.g.f.: (11 + x + x^2)*exp(x). (End)
%F A189836 From _Amiram Eldar_, Nov 02 2020: (Start)
%F A189836 Sum_{n>=0} 1/a(n) = (1 + sqrt(11)*Pi*coth(sqrt(11)*Pi))/22.
%F A189836 Sum_{n>=0} (-1)^n/a(n) = (1 + sqrt(11)*Pi*cosech(sqrt(11)*Pi))/22. (End)
%F A189836 From _Amiram Eldar_, Feb 12 2024: (Start)
%F A189836 Product_{n>=0} (1 - 1/a(n)) = sqrt(10/11)*sinh(sqrt(10)*Pi)/sinh(sqrt(11)*Pi).
%F A189836 Product_{n>=0} (1 + 1/a(n)) = 2*sqrt(3/11)*sinh(2*sqrt(3)*Pi)/sinh(sqrt(11)*Pi). (End)
%t A189836 Table[n^2+11,{n,0,100}]
%t A189836 LinearRecurrence[{3,-3,1},{11,12,15},60] (* _Harvey P. Dale_, Aug 24 2020 *)
%o A189836 (PARI) a(n)=n^2+11 \\ _Charles R Greathouse IV_, Jun 17 2017
%o A189836 (Magma) [n^2 + 11: n in [0..50]]; // _G. C. Greubel_, Jan 13 2018
%Y A189836 Cf. A002522, A059100, A117950, A087475.
%K A189836 nonn,easy
%O A189836 0,1
%A A189836 _Vladimir Joseph Stephan Orlovsky_, Apr 28 2011