A274454 - OEIS

%I #10 Oct 02 2019 16:02:18

%S 2,5,10,12,24,29,58,60,70,120,140,145,169,290,338,348,350,408,696,700,

%T 816,840,845,985,1680,1690,1740,1970,2028,2030,2040,2378,3480,4056,

%U 4060,4080,4200,4756,4896,4901,4925,5741,8400,9792,9802,9850,10140,10150

%N Products of distinct numbers in the Pell sequence (A000129).

%H Clark Kimberling, <a href="/A274454/b274454.txt">Table of n, a(n) for n = 1..10000</a>

%e The numbers in A274454 are 1, 2, 5, 12, 29, 70, 169, 408,..., so that the sequence of all products of distinct members, in increasing order, is (2, 5, 10, 12, 24, 29, 58, 60,...).

%t r[1] = 1; r[2] = 2; r[n_] := r[n] = 2 r[n - 1] + r[n - 2]

%t s = {1}; z = 30; f = Map[r, Range[z]]; Take[f, 20] (* A000129 *)

%t Do[s = Union[s, Select[s*f[[i]], # <= f[[z]] &]], {i, z}];

%t Take[s, 2 z]  (* A274454 *)

%Y Cf. A160009, A274280.

%K nonn,easy

%O 1,1

%A _Clark Kimberling_, Jun 23 2016