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 A160049 #11 Feb 16 2025 08:33:10 %S A160049 1,1,1,3,6,5,10,35,140,126,1260,1155,13860,12870,12012,45045,360360, %T A160049 340340,2042040,1939938,369512,117572,2586584,7436429,178474296, %U A160049 171609900,1487285800,1434168450,40156716600,38818159380,1164544781400 %N A160049 Denominator of the Harary number for the path graph P_n. %C A160049 Is this the same as A096620? - _R. J. Mathar_, Jan 26 2010 %C A160049 Yes, except for offset, because n*(harmonic(n)-harmonic(n-1)) = 1 which is an integer. - _Andrew Howroyd_, Oct 31 2017 %H A160049 Andrew Howroyd, <a href="/A160049/b160049.txt">Table of n, a(n) for n = 1..200</a> %H A160049 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HararyIndex.html">Harary Index</a> %H A160049 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HarmonicNumber.html">Harmonic Number</a> %e A160049 0, 2, 5, 26/3, 77/6, 87/5, 223/10, 962/35, 4609/140, 4861/126, ... %o A160049 (PARI) %o A160049 harmonic(n)=sum(k=1,n,1/k); %o A160049 a(n)=denominator(2*n*harmonic(n)); \\ _Andrew Howroyd_, Oct 31 2017 %Y A160049 Cf. A160048. %K A160049 nonn,frac %O A160049 1,4 %A A160049 _Eric W. Weisstein_, Apr 30 2009