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 A160048 #13 Feb 16 2025 08:33:10 %S A160048 0,2,5,26,77,87,223,962,4609,4861,55991,58301,785633,811373,835397, %T A160048 3431678,29889983,30570663,197698279,201578155,41054655,13920029, %U A160048 325333835,990874363,25128807667,25472027467,232222818803,235091155703 %N A160048 Numerator of the Harary number for the path graph P_n. %H A160048 Andrew Howroyd, <a href="/A160048/b160048.txt">Table of n, a(n) for n = 1..200</a> %H A160048 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HararyIndex.html">Harary Index</a> %e A160048 0, 2, 5, 26/3, 77/6, 87/5, 223/10, 962/35, 4609/140, 4861/126, ... %o A160048 (PARI) %o A160048 harmonic(n)=sum(k=1,n,1/k); %o A160048 a(n)=numerator(2*n*(harmonic(n)-1)); \\ _Andrew Howroyd_, Oct 31 2017 %Y A160048 Cf. A160049, A027612. %K A160048 nonn,frac %O A160048 1,2 %A A160048 _Eric W. Weisstein_, Apr 30 2009