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 A083250 #14 Jan 27 2019 05:45:53
%S A083250 3,825,1755,4641,5313,56865,58395,140049,159152763,361701435
%N A083250 Numbers n for which abs(A045763(n) - A073757(n)) = 3, i.e., signed difference of size of related and unrelated sets to n equals either 3 or -3.
%C A083250 No more terms below 10^9. - _Amiram Eldar_, Jan 27 2019
%e A083250 For n=140049: d=40 divisors, r=70026 coprimes and u=70023 unrelated numbers to n; abs(r-u) = 3.
%t A083250 Do[r=EulerPhi[n]; d=DivisorSigma[0, n]; u=n-r-d+1; df=2*u-n; If[Equal[Abs[df], 3], Print[n(*, {d, r, u}*)]], {n, 1, 100}]
%o A083250 (PARI) isok(n) = abs(n-2*eulerphi(n)-2*numdiv(n)+2) == 3; \\ _Michel Marcus_, Jul 30 2017
%Y A083250 Cf. A000005, A000010, A045763, A073757, A083243-A083249.
%K A083250 nonn,more
%O A083250 1,1
%A A083250 _Labos Elemer_, May 07 2003
%E A083250 a(9)-a(10) from _Amiram Eldar_, Jan 27 2019