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A257761 Positive integers whose square is the sum of 23 consecutive squares.

%I A257761 #20 Sep 08 2022 08:46:12
%S A257761 92,138,4278,6532,205252,313398,9847818,15036572,472490012,721442058,
%T A257761 22669672758,34614182212,1087671802372,1660759304118,52185576841098,
%U A257761 79681832415452,2503820016570332,3823067196637578,120131175218534838,183427543606188292
%N A257761 Positive integers whose square is the sum of 23 consecutive squares.
%C A257761 Positive integers x in the solutions to 2*x^2-46*y^2-1012*y-7590 = 0.
%H A257761 Colin Barker, <a href="/A257761/b257761.txt">Table of n, a(n) for n = 1..1000</a>
%H A257761 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,48,0,-1).
%F A257761 a(n) = 48*a(n-2)-a(n-4).
%F A257761 G.f.: -46*x*(x-1)*(x+2)*(2*x+1) / (x^4-48*x^2+1).
%e A257761 92 is in the sequence because 92^2 = 8464 = 7^2+8^2+...+29^2.
%t A257761 LinearRecurrence[{0, 48, 0, -1}, {92, 138, 4278, 6532}, 30] (* _Vincenzo Librandi_, May 11 2015 *)
%o A257761 (PARI) Vec(-46*x*(x-1)*(x+2)*(2*x+1)/(x^4-48*x^2+1) + O(x^100))
%o A257761 (Magma) I:=[92,138,4278,6532]; [n le 4 select I[n] else 48*Self(n-2)-Self(n-4): n in [1..30]]; // _Vincenzo Librandi_, May 11 2015
%Y A257761 Cf. A001032, A001653, A180274, A218395, A257765, A257767, A257780, A257781, A257823-A257828.
%K A257761 nonn,easy
%O A257761 1,1
%A A257761 _Colin Barker_, May 07 2015