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A041760 Numerators of continued fraction convergents to sqrt(401). 2
20, 801, 32060, 1283201, 51360100, 2055687201, 82278848140, 3293209612801, 131810663360180, 5275719744020001, 211160600424160220, 8451699736710428801, 338279150068841312260, 13539617702490362919201, 541922987249683358080300 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

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

Tanya Khovanova, Recursive Sequences

Index entries for linear recurrences with constant coefficients, signature (40,1).

FORMULA

a(n) = 40*a(n-1)+a(n-2) for n>1, a(0)=20, a(1)=801. G.f.: (20+x)/(1-40*x-x^2). [Philippe Deléham, Nov 23 2008]

a(n) = (1/2)*sqrt(401)*((20+sqrt(401))^n-(20-sqrt(401))^n)+10*((20-sqrt(401))^n+(20+sqrt(401))^n). [Paolo P. Lava, Nov 28 2008]

MATHEMATICA

Numerator[Convergents[Sqrt[401], 30]] (* Vincenzo Librandi, Nov 07 2013 *)

CROSSREFS

Cf. A041761, A040380.

Sequence in context: A267671 A281777 A041763 * A250550 A117798 A006424

Adjacent sequences:  A041757 A041758 A041759 * A041761 A041762 A041763

KEYWORD

nonn,cofr,frac,easy,less

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified May 28 04:27 EDT 2017. Contains 287212 sequences.