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 A064596 #7 Jul 30 2017 22:41:44 %S A064596 1,24,2520,186076800 %N A064596 Smallest nonunitary multiperfect number of index n; i.e., smallest k such that sigma(k) - usigma(k) = nk. %C A064596 4.5*10^14 < a(4) <= 1081895452249824576000. %t A064596 nusigma[ n_ ] := DivisorSigma[ 1, n ]-Times@@(1+Power@@#&/@FactorInteger[ n ]); a[ n_ ] := For[ k=1, True, k++, If[ nusigma[ k ]==n k, Return[ k ] ] ] %Y A064596 Cf. A048146, A064591, A064592, A064593, A064594, A064595. %K A064596 nonn,hard,more %O A064596 0,2 %A A064596 _Dean Hickerson_, Sep 25 2001