A041781 Denominators of continued fraction convergents to sqrt(411).

1, 3, 4, 7, 11, 216, 227, 443, 670, 2453, 98790, 298823, 397613, 696436, 1094049, 21483367, 22577416, 44060783, 66638199, 243975380, 9825653399, 29720935577, 39546588976, 69267524553, 108814113529, 2136735681604, 2245549795133, 4382285476737, 6627835271870

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,99460,0,0,0,0,0,0,0,0,0,-1).

Formula

G.f.: -(x^18 -3*x^17 +4*x^16 -7*x^15 +11*x^14 -216*x^13 +227*x^12 -443*x^11 +670*x^10 -2453*x^9 -670*x^8 -443*x^7 -227*x^6 -216*x^5 -11*x^4 -7*x^3 -4*x^2 -3*x -1) / (x^20 -99460*x^10 +1). - Colin Barker, Nov 24 2013

a(n) = 99460*a(n-10) - a(n-20) for n>19. - Vincenzo Librandi, Dec 24 2013

Mathematica

Denominator[Convergents[Sqrt[411], 30]] (* Vincenzo Librandi, Dec 24 2013 *)

Crossrefs

Cf. A041780, A040390.

Sequence in context: A111518 A291853 A041153 * A042893 A132111 A164831

Adjacent sequences: A041778 A041779 A041780 * A041782 A041783 A041784

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Extensions

More terms from Colin Barker, Nov 24 2013

Status

approved