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A041779 Denominators of continued fraction convergents to sqrt(410). 2
1, 4, 161, 648, 26081, 104972, 4224961, 17004816, 684417601, 2754675220, 110871426401, 446240380824, 17960486659361, 72288187018268, 2909487967390081, 11710240056578592, 471319090230533761, 1896986600978713636, 76350783129379079201 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (0, 162, 0, -1).

FORMULA

a(n) = 162*a(n-2)-a(n-4). G.f.: -(x^2-4*x-1)/(x^4-162*x^2+1). [Colin Barker, Jul 16 2012]

MATHEMATICA

Denominator[Convergents[Sqrt[410], 30]] (* Harvey P. Dale, Nov 06 2011 *)

CoefficientList[Series[(1 + 4 x - x^2)/(x^4 - 162 x^2 + 1), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 24 2013 *)

PROG

(MAGMA) I:=[1, 4, 161, 648]; [n le 4 select I[n] else 162*Self(n-2)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Dec 24 2013

CROSSREFS

Cf. A041778.

Sequence in context: A214007 A248330 A157463 * A222394 A306350 A125532

Adjacent sequences:  A041776 A041777 A041778 * A041780 A041781 A041782

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Vincenzo Librandi, Dec 24 2013

STATUS

approved

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Last modified January 27 16:30 EST 2022. Contains 350608 sequences. (Running on oeis4.)