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 A250399 #12 Jan 10 2025 12:38:20 %S A250399 4,14,63,85,1649,3127,6401,11521,14121,30005,30629,33101,45671,58829, %T A250399 78227,82947,90581,110975,159877,185399,227341,308179,331918,336299, %U A250399 359413,439619,466759,476677,494321,618701,666409,898967,1044611,1113641,1228417,1248707 %N A250399 Composite numbers whose sum of aliquot parts divides the sum of their unrelated numbers. %C A250399 For a definition of unrelated number see A045763. %e A250399 There is no unrelated number to 4. Therefore 0 / (sigma(4)-4) = 0 / (7-4) = 0 is an integer. %e A250399 Unrelated numbers to 14 are 4, 6, 8, 10, 12 and their sum is 40. Now, 40 / (sigma(14) - 14) = 40 / (24 - 14) = 40 / 10 = 4, that is an integer. %p A250399 with(numtheory); P:=proc(q) local n; %p A250399 for n from 1 to q do if not isprime(n) then %p A250399 if type((1+n*(n+1)/2-sigma(n)-n*phi(n)/2)/(sigma(n)-n),integer) %p A250399 then print(n); fi; fi; od; end: P(10^5); %Y A250399 Cf. A000203, A045763, A066760, A112774, A250398. %K A250399 nonn %O A250399 1,1 %A A250399 _Paolo P. Lava_, Nov 21 2014