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 A010023 #35 Jul 08 2025 01:28:10
%S A010023 1,44,170,380,674,1052,1514,2060,2690,3404,4202,5084,6050,7100,8234,
%T A010023 9452,10754,12140,13610,15164,16802,18524,20330,22220,24194,26252,
%U A010023 28394,30620,32930,35324,37802,40364,43010,45740,48554,51452,54434,57500,60650,63884
%N A010023 a(0) = 1, a(n) = 42*n^2 + 2 for n>0.
%C A010023 First bisection of A007899. - _Bruno Berselli_, Feb 07 2012
%H A010023 Bruno Berselli, <a href="/A010023/b010023.txt">Table of n, a(n) for n = 0..1000</a>
%H A010023 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A010023 G.f.: (1+x)*(1+40*x+x^2)/(1-x)^3. - _Bruno Berselli_, Feb 07 2012
%F A010023 E.g.f.: (x*(x+1)*42+2)*e^x-1. - _Gopinath A. R._, Feb 14 2012
%F A010023 Sum_{n>=0} 1/a(n) = 3/4 + sqrt(21)/84*Pi*coth(Pi/sqrt(21)) = 1.0379904347... - _R. J. Mathar_, May 07 2024
%t A010023 Join[{1}, 42 Range[39]^2 + 2] (* _Bruno Berselli_, Feb 07 2012 *)
%t A010023 Join[{1}, LinearRecurrence[{3, -3, 1}, {44, 170, 380}, 50]] (* _Vincenzo Librandi_, Aug 03 2015 *)
%o A010023 (Magma) [1] cat [42*n^2+2: n in [1..50]]; // _Vincenzo Librandi_, Aug 03 2015
%Y A010023 Cf. A206399.
%K A010023 nonn,easy
%O A010023 0,2
%A A010023 _N. J. A. Sloane_