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 A067705 #25 Jan 28 2025 14:34:07
%S A067705 33,88,165,264,385,528,693,880,1089,1320,1573,1848,2145,2464,2805,
%T A067705 3168,3553,3960,4389,4840,5313,5808,6325,6864,7425,8008,8613,9240,
%U A067705 9889,10560,11253,11968,12705,13464,14245,15048,15873,16720,17589,18480,19393,20328,21285
%N A067705 a(n) = 11*n^2 + 22*n.
%C A067705 Numbers k such that 11*(11 + k) is a perfect square.
%H A067705 Vincenzo Librandi, <a href="/A067705/b067705.txt">Table of n, a(n) for n = 1..1000</a>
%H A067705 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A067705 From _Vincenzo Librandi_, Jul 07 2012: (Start)
%F A067705 G.f.: 11*x*(3-x)/(1-x)^3.
%F A067705 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). (End)
%F A067705 From _Elmo R. Oliveira_, Jan 28 2025: (Start)
%F A067705 E.g.f.: 11*exp(x)*x*(3 + x).
%F A067705 a(n) = 11*A005563(n). (End)
%t A067705 Select[ Range[20000], IntegerQ[ Sqrt[ 11(11 + # )]] & ]
%t A067705 CoefficientList[Series[11 (3 - x)/(1 - x)^3, {x, 0, 50}], x] (* _Vincenzo Librandi_, Jul 07 2012 *)
%o A067705 (PARI) a(n)=11*n*(n+2) \\ _Charles R Greathouse IV_, Dec 07 2011
%o A067705 (Magma) [11*n*(n+2): n in [1..50]]; // _Vincenzo Librandi_, Jul 07 2012
%Y A067705 Cf. A067724, A067725, A067726, A067727, A067728 (if 11 is replaced by 3, 5, 6, 7, 8 respectively), A067707 (12).
%Y A067705 Cf. A005563.
%K A067705 nonn,easy
%O A067705 1,1
%A A067705 _Robert G. Wilson v_, Feb 05 2002