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 A241847 #21 Nov 29 2024 18:56:30
%S A241847 17,18,21,26,33,42,53,66,81,98,117,138,161,186,213,242,273,306,341,
%T A241847 378,417,458,501,546,593,642,693,746,801,858,917,978,1041,1106,1173,
%U A241847 1242,1313,1386,1461,1538,1617,1698,1781,1866,1953,2042,2133,2226,2321,2418,2517
%N A241847 a(n) = n^2 + 17.
%H A241847 Vincenzo Librandi, <a href="/A241847/b241847.txt">Table of n, a(n) for n = 0..1000</a>
%H A241847 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A241847 G.f.: (17 - 33*x + 18*x^2)/(1 - x)^3.
%F A241847 a(n) = a(-n) = 3*a(n-1) - 3*a(n-2) + a(n-3) = a(n-1) + 2*n - 1.
%F A241847 From _Amiram Eldar_, Nov 03 2020: (Start)
%F A241847 Sum_{n>=0} 1/a(n) = (1 + sqrt(17)*Pi*coth(sqrt(17)*Pi))/34.
%F A241847 Sum_{n>=0} (-1)^n/a(n) = (1 + sqrt(17)*Pi*cosech(sqrt(17)*Pi))/34. (End)
%F A241847 E.g.f.: exp(x)*(17 + x + x^2). - _Elmo R. Oliveira_, Nov 29 2024
%t A241847 Table[n^2 + 17, {n, 0, 60}]
%o A241847 (Magma) [n^2+17: n in [0..60]];
%o A241847 (PARI) a(n)=n^2+17 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A241847 Cf. similar sequences listed in A114962.
%K A241847 nonn,easy
%O A241847 0,1
%A A241847 _Vincenzo Librandi_, May 01 2014