This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A025619 #19 Jul 06 2025 10:01:40
%S A025619 1,4,7,16,28,49,64,112,196,256,343,448,784,1024,1372,1792,2401,3136,
%T A025619 4096,5488,7168,9604,12544,16384,16807,21952,28672,38416,50176,65536,
%U A025619 67228,87808,114688,117649,153664,200704,262144,268912,351232,458752,470596
%N A025619 Numbers of form 4^i*7^j, with i, j >= 0.
%H A025619 Amiram Eldar, <a href="/A025619/b025619.txt">Table of n, a(n) for n = 1..10000</a>
%F A025619 Sum_{n>=1} 1/a(n) = (4*7)/((4-1)*(7-1)) = 14/9. - _Amiram Eldar_, Sep 24 2020
%F A025619 a(n) ~ exp(sqrt(2*log(4)*log(7)*n)) / sqrt(28). - _Vaclav Kotesovec_, Sep 24 2020
%F A025619 a(n) = 4^A025648(n) * 7^A025666(n). - _R. J. Mathar_, Jul 06 2025
%t A025619 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 A025619 Subsequence of A003591.
%K A025619 easy,nonn
%O A025619 1,2
%A A025619 _David W. Wilson_