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%I #42 May 29 2024 06:58:46
%S 4,4,4,24,24,64,144,224,544,1024,1984,4224,8064,16384,33024,65024,
%T 131584,262144,523264,1050624,2095104,4194304,8392704,16769024,
%U 33562624,67108864,134201344,268468224,536838144,1073741824,2147549184,4294836224,8590065664
%N Number of solutions of y^2 + y = x^3 + x where x and y are in GF(2^n).
%H Paolo Xausa, <a href="/A362374/b362374.txt">Table of n, a(n) for n = 1..1000</a>
%H John C. Baez, <a href="https://arxiv.org/abs/2304.08737">Motivating Motives</a>, arXiv:2304.08737 [math.NT], 2023. See pp. 4-5.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,2,4).
%F a(n) = 4 * A038518(n). - _Joerg Arndt_, Apr 20 2023
%F From _Stefano Spezia_, May 28 2024: (Start)
%F G.f.: 4*x*(1 + x - x^2)/((1 - 2*x)*(1 + 2*x + 2*x^2)).
%F E.g.f.: 2*cosh(x)*(cosh(x) - cos(x)) + 2*(cosh(x) + cos(x))*sinh(x). (End)
%t LinearRecurrence[{0, 2, 4}, {4, 4, 4}, 50] (* _Paolo Xausa_, May 28 2024 *)
%Y Cf. A038518.
%K nonn,easy
%O 1,1
%A _Michel Marcus_, Apr 20 2023
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