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A084864 Numbers that can be written in the form 2*u^2 + 3*v^2, u*v>0. 4

%I #7 Dec 13 2021 08:04:59

%S 5,11,14,20,21,29,30,35,44,45,50,53,56,59,62,66,75,77,80,83,84,93,98,

%T 99,101,107,110,116,120,125,126,131,140,146,147,149,155,158,165,173,

%U 174,176,179,180,189,194,197,200,203,206,210,212,219,224,227,236,237

%N Numbers that can be written in the form 2*u^2 + 3*v^2, u*v>0.

%C A084863(a(n)) > 0; for primes see A084865, A084866.

%H Jean-François Alcover, <a href="/A084864/b084864.txt">Table of n, a(n) for n = 1..10000</a>

%e 30 = 18 + 12 = 2*3^2 + 3*2^2, therefore 30 is a term.

%t wmax = 240;

%t Table[w = 2 u^2 + 3 v^2; If[w <= wmax, w, Nothing], {u, 1, Sqrt[wmax/2] // Ceiling}, {v, 1, Sqrt[wmax/3] // Ceiling}] // Flatten // Union (* _Jean-François Alcover_, Dec 13 2021 *)

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Jun 10 2003

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)