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 A103931 #5 Oct 16 2022 11:42:42 %S A103931 1,4,36,144,3600,400,19600,78400,6350400,6350400,768398400,768398400, %T A103931 129859329600,129859329600,129859329600,519437318400,150117385017600, %U A103931 16679709446400,6021375110150400,240855004406016,26761667156224 %N A103931 Denominators of squares of harmonic numbers A001008/A002805. %C A103931 The corresponding numerators are given in A103930. For the rational see the link there. %F A103931 a(n)=denominator(H(n)^2), with the harmonic numbers H(n)=A001008(n)/A002805(n), n>=1. %t A103931 Denominator[HarmonicNumber[Range[30]]^2] (* _Harvey P. Dale_, Oct 16 2022 *) %K A103931 nonn,easy,frac %O A103931 1,2 %A A103931 _Wolfdieter Lang_, Mar 24 2005