OFFSET
1,2
COMMENTS
Are 2,3,6,8,21 the only numbers that are a product of two distinct Fibonacci numbers and also a product of two distinct Lucas numbers (including 2)?
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
MATHEMATICA
z = 400; f[n_] := Fibonacci[n];
s = Join[{0}, Take[Sort[Flatten[Table[f[m] f[n], {n, 2, z}, {m, 2, n - 1}]]], z]]
g[n_] := LucasL[n - 1]; t = Take[Sort[Flatten[Table[g[u] g[v], {u, 1, z}, {v, 1, u - 1}]]], z]
Union[s, t]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 19 2016
STATUS
approved