A112816 Numbers k such that lcm(1,2,3,...,k)/9 equals the denominator of the k-th harmonic number H(k).

63, 64, 65, 69, 70, 71, 189, 190, 191, 192, 193, 194, 195, 196, 197, 207, 208, 209, 210, 211, 212, 213, 214, 215, 1701, 1702, 1703, 1704, 1705, 1706, 1707, 1708, 1709, 1710, 1711, 1712, 1713, 1714, 1715, 1716, 1717, 1718, 1719, 1720, 1721, 1722, 1723, 1724

Offset: 1

Author

Robert G. Wilson v, Sep 17 2005

Keywords

• nonn

Comments

When 9 occurs in A110566.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1483 from Jinyuan Wang)

Crossrefs

Cf. A002805, A003418, A110566.

Cf. A098464, A112813, A112814, A112815, A112817, A112818, A112819, A112820, A112821, A112822.

Programs

Mathematica

f[n_] := LCM @@ Range[n]/Denominator[ HarmonicNumber[n]]; Select[ Range[1724], f[ # ] == 9 &]

Extensions

Definition corrected by Jinyuan Wang, May 03 2020