A201225 - OEIS

%I #20 May 28 2026 23:31:35

%S 6100,2305180,748476100,241118603980,77641444770100,25000340035616380,

%T 8050032494909496100,2592085474592828222380,834643472994047002110100,

%U 268752606222334691877221980,86537504560185639786707316100,27864807715774753485364243735180

%N Values x for infinite sequence x^3-y^2 = d with decreasing coefficient r=sqrt(x)/d which tend to 1/(1350*sqrt(5))or infinity family of solutions Mordell curve with extension sqrt(5).

%C a(1) = A200656(4) = A201047(4).

%C a(2) = A200656(36) = A201047(26).

%C All points in this sequence are extremal points (definition see A200656) and from these reason is subset of A200656 and primary (definition see A200656) and from these reason is subset of A201047.

%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (341,-6138,6138,-341,1).

%F G.f.: z*(20*(-305-11254*z+7424*z^2-346*z^3+z^4))/((-1+z)*(1- 322*z+z^2)*(1-18*z+z^2)).

%F a(n) = 341*a(n-1) - 6138*a(n-2) + 6138*a(n-3) - 341*a(n-4) + a(n-5).

%t LinearRecurrence[{341,-6138,6138,-341,1},{6100,2305180,748476100,241118603980,77641444770100},20] (* _Harvey P. Dale_, Aug 17 2016 *)

%o (PARI) a(n)=([0,1,0,0,0; 0,0,1,0,0; 0,0,0,1,0; 0,0,0,0,1; 1,-341,6138,-6138,341]^(n-1)*[6100;2305180;748476100;241118603980;77641444770100])[1,1] \\ _Charles R Greathouse IV_, May 28 2026

%Y Cf. A200216, A200656, A201047.

%K nonn,easy

%O 1,1

%A _Artur Jasinski_, Nov 28 2011