A225905 Denominator of Sum_{k=1..n} 1/L(k) where L(n) is the n-th Lucas number (A000204).

1, 3, 12, 84, 924, 2772, 80388, 3778236, 35893242, 1471622922, 292852961478, 3367809056997, 1754628518695437, 493050613753417797, 61138276105423806828, 134932175364670341669396, 481842798227237790101413116, 154671538230943330622553610236

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Example

1, 4/3, 19/12, 145/84, 1679/924, 5191/2772, ... = A225904/A225905.

Mathematica

Denominator[Table[Sum[1/LucasL[k], {k, 1, n}], {n, 1, 30}]]
Denominator[Accumulate[1/LucasL[Range[20]]]] (* Harvey P. Dale, Mar 11 2015 *)

Crossrefs

Cf. A000204, A059248, A035105, A225904.

Sequence in context: A231868 A147835 A032183 * A355322 A070825 A232934

Adjacent sequences: A225902 A225903 A225904 * A225906 A225907 A225908

Keyword

nonn,frac,easy

Author

Michel Lagneau, May 20 2013

Status

approved