A081079 Lucas(4n+2) - 3, or 5*Fibonacci(2n)*Fibonacci(2n+2).

0, 15, 120, 840, 5775, 39600, 271440, 1860495, 12752040, 87403800, 599074575, 4106118240, 28143753120, 192900153615, 1322157322200, 9062201101800, 62113250390415, 425730551631120, 2918000611027440, 20000273725560975

Offset

0,2

References

Hugh C. Williams, Edouard Lucas and Primality Testing, John Wiley and Sons, 1998, p. 75.

Links

Table of n, a(n) for n=0..19.

Index entries for linear recurrences with constant coefficients, signature (8,-8,1).

Formula

a(n) = 8a(n-1) - 8a(n-2) + a(n-3).

G.f.: -15*x/(x-1)/(x^2-7*x+1). a(n) = 15*A092521(n) = 5*A058038(n). - R. J. Mathar, Sep 03 2010

Maple

luc := proc(n) option remember: if n=0 then RETURN(2) fi: if n=1 then RETURN(1) fi: luc(n-1)+luc(n-2): end: for n from 0 to 40 do printf(`%d, `, luc(4*n+2)-3) od: # James A. Sellers, Mar 05 2003

Mathematica

LinearRecurrence[{8, -8, 1}, {0, 15, 120}, 20] (* Jean-François Alcover, Nov 29 2023 *)

Crossrefs

Cf. A000032 (Lucas numbers), A000045 (Fibonacci numbers).

Sequence in context: A010967 A022580 A321950 * A138424 A279267 A357602

Adjacent sequences: A081076 A081077 A081078 * A081080 A081081 A081082

Keyword

nonn,easy

Author

R. K. Guy, Mar 04 2003

Status

approved