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 A274454 Products of distinct numbers in the Pell sequence (A000129). 1

%I

%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

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Last modified September 24 09:10 EDT 2021. Contains 347630 sequences. (Running on oeis4.)