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A176378 y-values in the solution to x^2-70*y^2=1. 2
0, 30, 15060, 7560090, 3795150120, 1905157800150, 956385420525180, 480103575945840210, 241011038739391260240, 120987061343598466800270, 60735263783447690942475300, 30488981432229397254655800330 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The corresponding values of x of this Pell equation are in A176377.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Index entries for linear recurrences with constant coefficients, signature (502,-1).

FORMULA

a(n) = 502*a(n-1)-a(n-2) with a(1)=0, a(2)=30.

G.f.: 30*x^2/(1-502*x+x^2).

a(n) = ((25+3r)^(2n-2)-(25-3r)^(2n-2))/(2r*5^(n-1)), where r=sqrt(70). - Bruno Berselli, Dec 14 2011

MATHEMATICA

LinearRecurrence[{502, -1}, {0, 30}, 20]

PROG

(Magma) I:=[0, 30]; [n le 2 select I[n] else 502*Self(n-1)-Self(n-2): n in [1..20]];

(Maxima) makelist(expand(((25+3*sqrt(70))^(2*n-2)-(25-3*sqrt(70))^(2*n-2))/(2*sqrt(70)*5^(n-1))), n, 1, 12); [Bruno Berselli, Dec 14 2011]

CROSSREFS

Cf. A176377.

Sequence in context: A250435 A137749 A007741 * A089037 A116076 A230473

Adjacent sequences:  A176375 A176376 A176377 * A176379 A176380 A176381

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Apr 16 2010

STATUS

approved

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Last modified October 2 23:51 EDT 2022. Contains 357230 sequences. (Running on oeis4.)