A274349 Products of two distinct Lucas numbers (2,3,4,7,11,18,...).

6, 8, 12, 14, 21, 22, 28, 33, 36, 44, 54, 58, 72, 77, 87, 94, 116, 126, 141, 152, 188, 198, 203, 228, 246, 304, 319, 329, 369, 398, 492, 517, 522, 532, 597, 644, 796, 836, 846, 861, 966, 1042, 1288, 1353, 1363, 1368, 1393, 1563, 1686, 2084, 2189, 2204, 2214

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

6 = 2*3, 44 = 4*11.

Maple

N:= 10000: # for terms <= N
L:= gfun:-rectoproc({f(n)=f(n-1)+f(n-2), f(0)=2, f(1)=1}, f(n), remember):
S:= {}:
for i from 2 do
  u:= L(i);
  if u > N then break fi;
  for j from 0 to i-1 do
    if j = 1 then next fi;
    v:= u*L(j);
    if v > N then break fi;
    S:= S union {v};
od od:
sort(convert(S, list)); # Robert Israel, Jan 01 2021

Mathematica

z = 100; f[n_] := LucasL[n]; f[1] = 2 ;
Take[Sort[Flatten[Table[f[u] f[v], {u, 1, z}, {v, 1, u - 1}]]], z]
Take[Times@@@Subsets[Join[{2}, LucasL[Range[2, 20]]], {2}]//Union, 60] (* Harvey P. Dale, Aug 13 2019 *)

Crossrefs

Cf. A000032, A274348, A274347, A271354.

Sequence in context: A123303 A063207 A096175 * A315859 A315860 A315861

Adjacent sequences: A274346 A274347 A274348 * A274350 A274351 A274352

Keyword

nonn,easy

Author

Clark Kimberling, Jun 18 2016

Status

approved