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A098258 Chebyshev polynomials S(n,531) + S(n-1,531) with Diophantine property. 3
1, 532, 282491, 150002189, 79650879868, 42294467207719, 22458282436418921, 11925305679271239332, 6332314857410591666371, 3362447263979344903603669, 1785453164858174733221881868, 948072268092426803995915668239 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

(23*a(n))^2 - 533*b(n)^2 = -4 with b(n)=A098259(n) give all positive solutions of this Pell equation.

LINKS

Muniru A Asiru, Table of n, a(n) for n = 0..300

Tanya Khovanova, Recursive Sequences

Giovanni Lucca, Integer Sequences and Circle Chains Inside a Hyperbola, Forum Geometricorum (2019) Vol. 19, 11-16.

Index entries for linear recurrences with constant coefficients, signature (531, -1).

Index entries for sequences related to Chebyshev polynomials.

FORMULA

a(n) = S(n, 531) + S(n-1, 531) = S(2*n, sqrt(533)), with S(n, x)=U(n, x/2) Chebyshev's polynomials of the second kind, A049310. S(-1, x)= 0 = U(-1, x). S(n, 531)=A098257(n).

a(n)= (-2/23)*I*((-1)^n)*T(2*n+1, 23*I/2) with the imaginary unit I and Chebyshev's polynomials of the first kind. See the T-triangle A053120.

G.f.: (1+x)/(1-531*x+x^2).

a(n) = 531*a(n-1)-a(n-2), n>1 ; a(0)=1, a(1)=532 . [Philippe Deléham, Nov 18 2008]

EXAMPLE

All positive solutions of Pell equation x^2 - 533*y^2 = -4 are (23=23*1,1), (12236=23*532,530), (6497293=23*282491,281429), (3450050347=23*150002189,149438269), ...

MATHEMATICA

LinearRecurrence[{531, -1}, {1, 532}, 20] (* Harvey P. Dale, Oct 09 2018 *)

PROG

(GAP) a:=[1, 532];; for n in [3..12] do a[n]:=531*a[n-1]-a[n-2]; od; Print(a); # Muniru A Asiru, Apr 29 2019

CROSSREFS

Sequence in context: A191950 A048055 A067803 * A160176 A077085 A165989

Adjacent sequences:  A098255 A098256 A098257 * A098259 A098260 A098261

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang, Sep 10 2004

STATUS

approved

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Last modified November 14 20:11 EST 2019. Contains 329129 sequences. (Running on oeis4.)