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%I #12 Sep 24 2020 04:00:16
%S 1,2,3,4,6,7,8,9,12,14,16,18,21,24,27,28,32,36,42,48,49,54,56,63,64,
%T 72,81,84,96,98,108,112,126,128,144,147,162,168,189,192,196,216,224,
%U 243,252,256,288,294,324,336,343,378,384,392,432,441,448,486,504,512,567
%N Numbers of the form (2^i)*(3^j)*(7^k), with i, j, k >= 0.
%C Numbers m | 42^e with integer e >= 0. - _Michael De Vlieger_, Aug 22 2019
%C Sum_{n>=1} 1/a(n) = (2*3*7)/((2-1)*(3-1)*(7-1)) = 7/2. - _Amiram Eldar_, Sep 24 2020
%H Michael De Vlieger, <a href="/A108319/b108319.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) ~ exp((6*log(2)*log(3)*log(7)*n)^(1/3)) / sqrt(42). - _Vaclav Kotesovec_, Sep 23 2020
%t With[{n = 567}, Sort@ Flatten@ Table[2^i * 3^j * 7^k, {i, 0, Log2@ n}, {j, 0, Log[3, n/2^i]}, {k, 0, Log[7, n/(2^i*3^j)]}]] (* _Michael De Vlieger_, Aug 22 2019 *)
%Y Cf. A051037, A003586, A003591, A003594.
%K nonn,easy
%O 1,2
%A Douglas Winston (douglas.winston(AT)srupc.com), Jun 30 2005
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