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 A027691 #35 Oct 28 2024 18:49:19
%S A027691 6,8,12,18,26,36,48,62,78,96,116,138,162,188,216,246,278,312,348,386,
%T A027691 426,468,512,558,606,656,708,762,818,876,936,998,1062,1128,1196,1266,
%U A027691 1338,1412,1488,1566,1646,1728,1812,1898,1986,2076,2168,2262,2358,2456,2556
%N A027691 a(n) = n^2 + n + 6.
%H A027691 Muniru A Asiru, <a href="/A027691/b027691.txt">Table of n, a(n) for n = 0..2000</a>
%H A027691 Patrick De Geest, <a href="http://www.worldofnumbers.com/quasimor.htm">Palindromic Quasi_Over_Squares of the form n^2+(n+X)</a>.
%H A027691 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A027691 a(n) = 2*n + a(n-1), with a(0)=6. - _Vincenzo Librandi_, Aug 05 2010
%F A027691 Sum_{n>=0} 1/a(n) = Pi*tanh(Pi*sqrt(23)/2)/sqrt(23). - _Amiram Eldar_, Jan 17 2021
%F A027691 From _Elmo R. Oliveira_, Oct 28 2024: (Start)
%F A027691 G.f.: 2*(3 - 5*x + 3*x^2)/(1 - x)^3.
%F A027691 E.g.f.: (2*(3 + x) + x^2)*exp(x).
%F A027691 a(n) = 2*A152950(n+1). (End)
%t A027691 Table[n^2+n+6,{n,0,100}] (* _Vladimir Joseph Stephan Orlovsky_, Mar 12 2011 *)
%o A027691 (PARI) a(n)=n^2+n+6 \\ _Charles R Greathouse IV_, Jun 17 2017
%o A027691 (GAP) List([0..50],n->n^2+n+6); # _Muniru A Asiru_, Jul 15 2018
%Y A027691 Cf. A002061, A002378, A002522, A152950.
%K A027691 nonn,easy
%O A027691 0,1
%A A027691 _Patrick De Geest_
%E A027691 Offset changed by _Charles R Greathouse IV_, Jul 25 2010