A272909 - OEIS

%I #19 Sep 07 2016 13:57:43

%S 1,3,4,7,9,11,12,16,18,21,28,29,33,44,47,49,54,72,76,77,87,116,121,

%T 123,126,141,188,198,199,203,228,304,319,322,324,329,369,492,517,521,

%U 522,532,597,796,836,841,843,846,861,966,1288,1353,1363,1364,1368,1393

%N Numbers that are the product of two Lucas numbers L(i), for i >= 1, using the Lucas numbers as defined in A000204.

%C Conjecture: if c and d are consecutive terms, then d - c is a product of two Lucas numbers or a product of two Fibonacci numbers.

%H Clark Kimberling, <a href="/A272909/b272909.txt">Table of n, a(n) for n = 1..1000</a>

%t Take[Union@Flatten@Table[LucasL[i] LucasL[j], {i, 0, 15}, {j, i}], 60] (* adapted by _Vincenzo Librandi_, Sep 04 2016 *)

%Y Cf. A049997 (Fibonacci(i)*Fibonacci(j)), A000204.

%K nonn,easy

%O 1,2

%A _Clark Kimberling_, May 10 2016