A112815 Numbers k such that lcm(1,2,3,...,k)/7 equals the denominator of the k-th harmonic number H(k).

44, 45, 46, 47, 48, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 332, 333, 334, 335, 2209, 2210, 2211, 2212, 2213, 2214, 2215, 2216, 2217, 2218, 2219

Offset

1,1

Comments

When 7 occurs in A110566.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

f[n_] := LCM @@ Range[n]/Denominator[ HarmonicNumber[n]]; Select[ Range[2219], f[ # ] == 7 &]

Prog

(PARI) isok(n) = lcm(vector(n, i, i)) == 7*denominator(sum(i=1, n, 1/i)); \\ Michel Marcus, Mar 07 2018

Crossrefs

Cf. A002805, A003418, A110566.

Cf. A098464, A112813, A112814, A112816, A112817, A112818, A112819, A112820, A112821, A112822.

Sequence in context: A059070 A059071 A085519 * A354145 A242934 A369276

Adjacent sequences: A112812 A112813 A112814 * A112816 A112817 A112818

Keyword

nonn

Author

Robert G. Wilson v, Sep 17 2005

Status

approved