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 A387723 #9 Sep 06 2025 21:40:47
%S A387723 12,18,20,24,28,30,36,40,42,44,45,48,50,52,54,56,60,66,68,70,72,75,76,
%T A387723 78,80,84,88,90,92,96,98,100,102,104,105,108,110,112,114,116,120,124,
%U A387723 126,130,132,135,136,138,140,144,148,150,152,154,156,160,162,164,165,168,170,172,174,176,180,182,184,186,188
%N A387723 Numbers k for which A107758(k) > 2*k, and also for some of the proper divisors d|k, d<k, A107758(d) > 2*d.
%C A387723 Not the same as positions of terms > 1 in A387725. For example, A387725(225) = 3, although 225 is not present in this sequence.
%H A387723 Antti Karttunen, <a href="/A387723/b387723.txt">Table of n, a(n) for n = 1..10000</a>
%o A387723 (PARI)
%o A387723 A107758(n) = { my(f = factor(n)); prod(k=1, #f~, 1+sigma(f[k, 1]^f[k, 2])); };
%o A387723 is_A387723(n) = if((A107758(n)<=(2*n)), 0, fordiv(n, d, if(d<n && A107758(d)>(2*d), return(1))); (0));
%Y A387723 Cf. A107758, A387725.
%Y A387723 Setwise difference A387721 \ A387722.
%Y A387723 Cf. also A341610, A387713.
%K A387723 nonn,new
%O A387723 1,1
%A A387723 _Antti Karttunen_, Sep 06 2025