A042243 Denominators of continued fraction convergents to sqrt(647).

1, 2, 7, 16, 39, 55, 94, 431, 10869, 43907, 54776, 98683, 252142, 602967, 2061043, 4725053, 238313693, 481352439, 1682371010, 3846094459, 9374559928, 13220654387, 22595214315, 103601511647, 2612633005490, 10554133533607, 13166766539097

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, 0, 0, 0, 0, 0, 0, 240374736, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1).

Formula

a(n) = 240374736*a(n-16) - a(n-32) for n>31. - Vincenzo Librandi, Jan 18 2014

Mathematica

Denominator[Convergents[Sqrt[647], 30]] (* Harvey P. Dale, May 12 2012 *)
LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 240374736, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1}, {1, 2, 7, 16, 39, 55, 94, 431, 10869, 43907, 54776, 98683, 252142, 602967, 2061043, 4725053, 238313693, 481352439, 1682371010, 3846094459, 9374559928, 13220654387, 22595214315, 103601511647, 2612633005490, 10554133533607, 13166766539097, 23720900072704, 60608566684505, 144938033441714, 495422667009647, 1135783367461008}, 40]

Crossrefs

Cf. A042242.

Sequence in context: A176805 A224227 A260505 * A293378 A377728 A041887

Adjacent sequences: A042240 A042241 A042242 * A042244 A042245 A042246

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Extensions

More terms from Vincenzo Librandi, Jan 18 2014

Status

approved