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 A241750 #23 Jul 04 2025 14:57:38
%S A241750 15,16,19,24,31,40,51,64,79,96,115,136,159,184,211,240,271,304,339,
%T A241750 376,415,456,499,544,591,640,691,744,799,856,915,976,1039,1104,1171,
%U A241750 1240,1311,1384,1459,1536,1615,1696,1779,1864,1951,2040,2131,2224,2319,2416,2515
%N A241750 a(n) = n^2 + 15.
%H A241750 Vincenzo Librandi, <a href="/A241750/b241750.txt">Table of n, a(n) for n = 0..1000</a>
%H A241750 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A241750 G.f.: (15 - 29*x + 16*x^2)/(1 - x)^3.
%F A241750 a(n) = a(-n) = 3*a(n-1) - 3*a(n-2) + a(n-3) = a(n-1) + 2*n - 1.
%F A241750 From _Amiram Eldar_, Nov 03 2020: (Start)
%F A241750 Sum_{n>=0} 1/a(n) = (1 + sqrt(15)*Pi*coth(sqrt(15)*Pi))/30.
%F A241750 Sum_{n>=0} (-1)^n/a(n) = (1 + sqrt(15)*Pi*cosech(sqrt(15)*Pi))/30. (End)
%F A241750 E.g.f.: exp(x)*(15 + x + x^2). - _Elmo R. Oliveira_, Nov 29 2024
%t A241750 Table[n^2 + 15, {n, 0, 60}]
%t A241750 LinearRecurrence[{3,-3,1},{15,16,19},60] (* _Harvey P. Dale_, Jul 04 2025 *)
%o A241750 (Magma) [n^2+15: n in [0..60]];
%o A241750 (PARI) a(n)=n^2+15 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A241750 Cf. similar sequences listed in A114962.
%K A241750 nonn,easy
%O A241750 0,1
%A A241750 _Vincenzo Librandi_, May 01 2014