login
Numbers k such that lcm(1,2,3,...,k)/17 equals the denominator of the k-th harmonic number H(k).
12

%I #13 Mar 15 2021 10:05:44

%S 272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,

%T 79507,79508,79509,79510,79511,79512,79513,79514,79515,79516,79517,

%U 79518,79519,79520,79521,79522,79523,79524,79525,79526,79527,79528

%N Numbers k such that lcm(1,2,3,...,k)/17 equals the denominator of the k-th harmonic number H(k).

%C When 17 occurs in A110566.

%H Chai Wah Wu, <a href="/A112820/b112820.txt">Table of n, a(n) for n = 1..10000</a> (n = 1..3106 from Jinyuan Wang)

%t a = h = 1; t = {}; Do[a = LCM[a, n]; h = h + 1/n; If[a/Denominator[h] == 17, AppendTo[t, n]], {n, 79528}]; t

%Y Cf. A002805, A003418, A110566.

%Y Cf. A098464, A112813, A112814, A112815, A112816, A112817, A112818, A112819, A112821, A112822.

%K nonn

%O 1,1

%A _Robert G. Wilson v_, Sep 17 2005

%E Definition corrected by _Jinyuan Wang_, May 03 2020