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 A230112 #11 Jan 12 2025 11:10:47
%S A230112 4,8,16,64,256,720,800,2200,4096,25600,33600,36288,41472,46080,65536,
%T A230112 92400,104960,235200,282240,338688,376320,403200,419840,535680,556640,
%U A230112 576000,580800,640000,844800,979776,1088640,1244160,1354752,1382400,1505280,1689600,1995840
%N A230112 Composite numbers m such that Product_{i=1..k} (p_i/(p_i-1)) / Sum_{i=1..k} (p_i/(p_i+1)) is an integer, where p_i are the k prime factors of m (with multiplicity).
%e A230112 Prime factors of 2200 are 2^3, 5^2 and 11.
%e A230112 Sum_{i=1..6} (p(i)/(p(i)+1)) = 3*(2/(2+1)) + 2*(5/(5+1)) + 11/(11+1) = 55/12.
%e A230112 Product_{i=1..6} (p(i)/(p(i)-1)) = (2/(2-1))^3*(5/(5-1))^2*11/(11-1) = 55/4.
%e A230112 The ratio is an integer: (55/4) / (55/12) = 3.
%p A230112 with(numtheory); P:=proc(q) local a, d, n, p;
%p A230112 for n from 2 to q do if not isprime(n) then p:=ifactors(n)[2];
%p A230112 a:=mul((op(1, d)/(op(1, d)-1))^op(2, d), d=p)/add((op(1, d)/(op(1, d)+1))*op(2, d), d=p); if type(a, integer) then print(n); fi; fi;
%p A230112 od; end: P(10^7);
%Y A230112 Cf. A199767, A198391, A227034, A227248, A230110, A230111.
%K A230112 nonn
%O A230112 1,1
%A A230112 _Paolo P. Lava_, Oct 09 2013