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%I #15 Sep 24 2020 04:09:57
%S 1,4,7,16,28,49,64,112,196,256,343,448,784,1024,1372,1792,2401,3136,
%T 4096,5488,7168,9604,12544,16384,16807,21952,28672,38416,50176,65536,
%U 67228,87808,114688,117649,153664,200704,262144,268912,351232,458752,470596
%N Numbers of form 4^i*7^j, with i, j >= 0.
%H Amiram Eldar, <a href="/A025619/b025619.txt">Table of n, a(n) for n = 1..10000</a>
%F Sum_{n>=1} 1/a(n) = (4*7)/((4-1)*(7-1)) = 14/9. - _Amiram Eldar_, Sep 24 2020
%F a(n) ~ exp(sqrt(2*log(4)*log(7)*n)) / sqrt(28). - _Vaclav Kotesovec_, Sep 24 2020
%t n=10^6; Flatten[Table[4^i*7^j, {i, 0, Log[4, n]}, {j, 0, Log[7, n/4^i]}]]//Sort (* _Amiram Eldar_, Sep 24 2020 *)
%Y Subsequence of A003591.
%K easy,nonn
%O 1,2
%A _David W. Wilson_
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