A042559 Denominators of continued fraction convergents to sqrt(808).

1, 2, 5, 7, 40, 47, 87, 134, 221, 3007, 3228, 6235, 9463, 15698, 87953, 103651, 295255, 694161, 39168271, 79030703, 197229677, 276260380, 1578531577, 1854791957, 3433323534, 5288115491, 8721439025, 118666822816, 127388261841, 246055084657, 373443346498

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, 0, 0, 39463526, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1).

Formula

a(n) = 39463526*a(n-18) - a(n-36) for n>35. - Vincenzo Librandi, Jan 25 2014

Mathematica

Denominator[Convergents[Sqrt[808], 30]] (* Vincenzo Librandi, Jan 25 2014 *)
LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 39463526, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1}, {1, 2, 5, 7, 40, 47, 87, 134, 221, 3007, 3228, 6235, 9463, 15698, 87953, 103651, 295255, 694161, 39168271, 79030703, 197229677, 276260380, 1578531577, 1854791957, 3433323534, 5288115491, 8721439025, 118666822816, 127388261841, 246055084657, 373443346498, 619498431155, 3470935502273, 4090433933428, 11651803369129, 27394040671686}, 40] (* Harvey P. Dale, Jul 14 2023 *)

Crossrefs

Cf. A040779, A042558.

Sequence in context: A028432 A019409 A123232 * A197222 A379642 A062645

Adjacent sequences: A042556 A042557 A042558 * A042560 A042561 A042562

Keyword

nonn,frac,easy

Author

N. J. A. Sloane

Extensions

More terms from Vincenzo Librandi, Jan 25 2014

Status

approved