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 A071639 #14 Sep 03 2020 06:41:55
%S A071639 24,3500,6048,52855,56320,67270,71874,80920,85536,95830,105600,112000,
%T A071639 117670,131625,142373,155925,250173,262392,280800,350142,360672,
%U A071639 673036,965419,984256,1041859,1078110,1144440,1166990,1283040,1331000,1355310,1454750,1480160,1691360
%N A071639 Numbers k such that core(k) = b(k,1)*b(k,0) where b(k,1) is the number of 1's in binary representation of k, b(k,0) the number of 0's and core(k) the squarefree part of k.
%H A071639 Amiram Eldar, <a href="/A071639/b071639.txt">Table of n, a(n) for n = 1..1000</a>
%t A071639 core[n_] := Times @@ (First[#]^Mod[Last[#], 2]& /@ FactorInteger[n]); b[n_] := Times @@ DigitCount[n, 2, {0, 1}]; Select[Range[10^5], core[#] == b[#] &] (* _Amiram Eldar_, Sep 03 2020 *)
%o A071639 (PARI) for(s=1,500000,b=binary(s); l=length(b); if(sum(i=1,l,if(component(b,i)-1,0,1))*sum(i=1,l,if(component(b,i),0,1))==core(s),print1(s,",")))
%Y A071639 Cf. A007913, A071295.
%K A071639 easy,nonn,base
%O A071639 1,1
%A A071639 _Benoit Cloitre_, Jun 22 2002
%E A071639 More terms from _Amiram Eldar_, Sep 03 2020