A112818 Numbers k such that lcm(1,2,3,...,k)/13 equals the denominator of the k-th harmonic number H(k).

156, 157, 158, 159, 160, 161, 27380, 27381, 27382, 27383, 27384, 27385, 27386, 27387, 27388, 27389, 27390, 27391, 27392, 27393, 27394, 27395, 27396, 27397, 27398, 27399, 27400, 27401, 27402, 27403, 27404, 27405, 27406, 27407, 27408

Offset: 1

Author

Robert G. Wilson v, Sep 17 2005

Keywords

• nonn

Comments

When 13 occurs in A110566.

Links

• Jinyuan Wang, Table of n, a(n) for n = 1..851

Crossrefs

Cf. A002805, A003418, A110566.

Cf. A098464, A112813, A112814, A112815, A112816, A112817, A112819, A112820, A112821, A112822.

Programs

Mathematica

a = h = 1; t = {}; Do[a = LCM[a, n]; h = h + 1/n; b = a/Denominator[h]; If[b == 13, AppendTo[t, n]], {n, 27408}]; t
With[{tk=Table[{LCM@@Range[k]/13,Denominator[HarmonicNumber[k]]},{k,28000}]},Position[ tk,?(#[[1]]==#[[2]]&),1,Heads->False]]//Flatten (* _Harvey P. Dale, Apr 02 2022 *)

Extensions

Definition corrected by Jinyuan Wang, May 03 2020