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A274347 Products of two distinct Lucas numbers (3,4,7,11,18,...).

%I A274347 #13 Sep 03 2019 08:08:20
%S A274347 12,21,28,33,44,54,72,77,87,116,126,141,188,198,203,228,304,319,329,
%T A274347 369,492,517,522,532,597,796,836,846,861,966,1288,1353,1363,1368,1393,
%U A274347 1563,2084,2189,2204,2214,2254,2529,3372,3542,3567,3572,3582,3647,4092
%N A274347 Products of two distinct Lucas numbers (3,4,7,11,18,...).
%C A274347 L(i)*L(j) = L(i+j) + (-1)^i*L(j-i). - _Robert Israel_, Sep 02 2019
%H A274347 Robert Israel, <a href="/A274347/b274347.txt">Table of n, a(n) for n = 1..10000</a>
%e A274347 12 = 3*4, 21 = 3*7.
%p A274347 L:= gfun:-rectoproc({f(n+1)=f(n)+f(n-1),f(0)=2,f(1)=1},f(n),remember):
%p A274347 Q:= proc(n) local j; op(sort([seq(L(n)+(-1)^j*L(n-2*j),j=2..(n-1)/2)])) end proc:
%p A274347 map(Q, [$5..20]); # _Robert Israel_, Sep 02 2019
%t A274347 z = 100; f[n_] := LucasL[n];
%t A274347 Take[Sort[Flatten[Table[f[u] f[v], {u, 2, z}, {v, 2, u - 1}]]], z]
%Y A274347 Cf. A000032, A274348, A274349, A271354.
%K A274347 nonn,easy
%O A274347 1,1
%A A274347 _Clark Kimberling_, Jun 18 2016