A041935 Denominators of continued fraction convergents to sqrt(490).

1, 7, 15, 22, 103, 434, 1839, 2273, 6385, 46968, 2072977, 14557807, 31188591, 45746398, 214174183, 902443130, 3823946703, 4726389833, 13276726369, 97663474416, 4310469600673, 30270950679127, 64852370958927, 95123321638054, 445345657511143, 1876505951682626

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,2079362,0,0,0,0,0,0,0,0,0,-1).

Formula

G.f.: -(x^18 -7*x^17 +15*x^16 -22*x^15 +103*x^14 -434*x^13 +1839*x^12 -2273*x^11 +6385*x^10 -46968*x^9 -6385*x^8 -2273*x^7 -1839*x^6 -434*x^5 -103*x^4 -22*x^3 -15*x^2 -7*x -1) / ((x^10 -1442*x^5 +1)*(x^10 +1442*x^5 +1)). - Colin Barker, Nov 27 2013

a(n) = 2079362*a(n-10) - a(n-20) for n>19. - Vincenzo Librandi, Dec 27 2013

Mathematica

Denominator[Convergents[Sqrt[490], 30]] (* Vincenzo Librandi, Dec 27 2013 *)

Crossrefs

Cf. A041934, A040467.

Sequence in context: A022389 A041225 A128840 * A041092 A367907 A349233

Adjacent sequences: A041932 A041933 A041934 * A041936 A041937 A041938

Keyword

nonn,frac,easy

Author

N. J. A. Sloane.

Extensions

More terms from Colin Barker, Nov 27 2013

Status

approved