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A159665 The general form of the recurrences are the a(j), b(j) and n(j) solutions of the 2 equations problem: 11*n(j) + 1 = a(j)*a(j) and 13*n(j) + 1 = b(j)*b(j); with positive integer numbers.

%I A159665 #22 Jul 07 2022 02:20:09
%S A159665 0,48,27600,15842400,9093510048,5219658925200,2996075129554800,
%T A159665 1719741904705530048,987128857225844692800,566610244305730148137200,
%U A159665 325233293102631879186060048,186683343630666392922650330400,107155914010709406905722103589600
%N A159665 The general form of the recurrences are the a(j), b(j) and n(j) solutions of the 2 equations problem: 11*n(j) + 1 = a(j)*a(j) and 13*n(j) + 1 = b(j)*b(j); with positive integer numbers.
%H A159665 Colin Barker, <a href="/A159665/b159665.txt">Table of n, a(n) for n = 1..363</a>
%H A159665 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (575,-575,1).
%F A159665 The a(j) recurrence is a(1)=1; a(2)=23; a(t+2) = 24*a(t+1) - a(t) resulting in terms 1, 23, 551, 13201, ... (A159664).
%F A159665 The b(j) recurrence is b(1)=1; b(2)=25; b(t+2) = 24*b(t+1) - b(t) resulting in terms 1, 25, 599, 14351, ... (A159661).
%F A159665 The n(j) recurrence is n(0)=n(1)=1; n(2)=48; n(t+3) = 575*(n(t+2) - n(t+1)) + n(t) resulting in terms 0, 0, 48, 27600, 15842400 as listed above.
%F A159665 From _Colin Barker_, Sep 25 2015: (Start)
%F A159665 a(n) = 575*a(n-1) - 575*a(n-2) + a(n-3) for n > 3.
%F A159665 G.f.: 48*x^2 / ((1-x)*(1-574*x+x^2)). (End)
%F A159665 a(n) = (-24 + (12 + sqrt(143))*(287 + 24*sqrt(143))^(-n) - (-12 + sqrt(143))*(287 + 24*sqrt(143))^n)/286. - _Colin Barker_, Jul 26 2016
%F A159665 From _G. C. Greubel_, Jun 25 2022: (Start)
%F A159665 a(n) = (12/143)*(ChebyshevU(n, 287) - 573*ChebyshevU(n-1, 287) - 1).
%F A159665 E.g.f.: (12/143)*(exp(287*x)*( (sqrt(143)/12)*sinh(24*sqrt(143)*x) + cosh(24*sqrt(143)*x) ) - exp(x)). (End)
%p A159665 for a from 1 by 2 to 100000 do b:=sqrt((13*a*a-2)/11): if (trunc(b)=b) then
%p A159665 n:=(a*a-1)/11: La:=[op(La),a]:Lb:=[op(Lb),b]:Ln:=[op(Ln),n]: endif: enddo:
%t A159665 LinearRecurrence[{575,-575,1}, {0,48,27600}, 30] (* _G. C. Greubel_, Jun 26 2022 *)
%o A159665 (PARI) concat(0, Vec(-48*x^2/((x-1)*(x^2-574*x+1)) + O(x^30))) \\ _Colin Barker_, Sep 25 2015
%o A159665 (PARI) a(n) = round((-24+(12+sqrt(143))*(287+24*sqrt(143))^(-n)-(-12+sqrt(143))*(287+24*sqrt(143))^n)/286) \\ _Colin Barker_, Jul 26 2016
%o A159665 (Magma) I:=[0,48,27600]; [n le 3 select I[n] else 575*Self(n-1) -575*Self(n-2) +Self(n-3): n in [1..31]]; // _G. C. Greubel_, Jun 26 2022
%o A159665 (SageMath) [(12/143)*(chebyshev_U(n,287) -573*chebyshev_U(n-1,287) -1) for n in (1..30)] # _G. C. Greubel_, Jun 26 2022
%Y A159665 Cf. A157456, A159661, A159664.
%K A159665 nonn,easy
%O A159665 1,2
%A A159665 _Paul Weisenhorn_, Apr 19 2009