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 A330680 #13 Mar 15 2021 01:50:13 %S A330680 1,9,27,49,88,125,243,289,361,484,841,968,1164,1331,1369,2401,3125, %T A330680 3488,3721,6889,7085,7761,7921,8342,8502,9156,10648,19683,22208,22801, %U A330680 25886,28561,29929,30877,32041,32761,33178,36481,59049,83521,87079,88307,92199 %N A330680 Numbers that begin a run of consecutive integers k such that the denominator of the k-th harmonic number is lcm(1..k). %C A330680 A098464 lists the numbers k such that lcm(1,2,3,...,k) equals the denominator of the k-th harmonic number H(k) = 1/1 + 1/2 + 1/3 + ... + 1/k. %H A330680 Chai Wah Wu, <a href="/A330680/b330680.txt">Table of n, a(n) for n = 1..308</a> %e A330680 The numbers k such that the denominator of the k-th harmonic number equals lcm(1..k) begin with the following runs of consecutive integers: %e A330680 1, 2, 3, 4, 5; %e A330680 9, 10, 11, 12, 13, 14, 15, 16, 17; %e A330680 27, 28, 29, 30, 31, 32; %e A330680 49, 50, 51, 52, 53; %e A330680 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99; %e A330680 125, 126, 127, ... %e A330680 so this sequence begins 1, 9, 27, 49, 88, 125, ... %Y A330680 Cf. A002805 (denominator of H(n)), A003418 (lcm(1..n)), A098464 (numbers k such that A002805(k)=A003418(k)). %K A330680 nonn %O A330680 1,2 %A A330680 _Jon E. Schoenfield_, Dec 24 2019