A112821 Numbers n such that lcm(1,2,3,...,n)/19 equals the denominator of the n-th harmonic number H(n).

343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 356, 357, 358, 359, 360

Offset: 1

Author

Robert G. Wilson v, Sep 17 2005

Keywords

• nonn
• more

Comments

Positions where 19 occurs in A110566.

Links

• Tanya Khovanova, Non Recursions

Crossrefs

Cf. A002805, A003418, A110566.

Cf. A098464, A112813, A112814, A112815, A112816, A112817, A112818, A112819, A112820, A112822.

Programs

Mathematica

a = h = 1; t = {}; Do[a = LCM[a, n]; h = h + 1/n; If[a/Denominator[h] == 19, AppendTo[t, n]], {n, 10^6}]; t
Select[Range[500],Denominator[HarmonicNumber[#]]==LCM@@Range[#]/19&] (* Harvey P. Dale, Jan 29 2012 *)

Extensions

Definition corrected by Max Alekseyev, Mar 03 2007