A129567 a(n) = number of positive divisors of the denominator of the n-th harmonic number H(n) = Sum_{k=1..n} 1/k.

1, 2, 4, 6, 12, 6, 12, 16, 48, 48, 96, 96, 192, 192, 192, 240, 480, 320, 640, 320, 160, 160, 320, 640, 1920, 1920, 3840, 3840, 7680, 7680, 15360, 18432, 9216, 9216, 9216, 9216, 18432, 18432, 18432, 18432, 36864, 18432, 36864, 73728, 73728, 73728, 147456

Offset

1,2

Comments

a(n) = A000005(A002805(n)).

The only n's where A129568(n) does not divide A129567(n), for n < 169, are n = 18 and 22. - Max Alekseyev, Jun 16 2007

Links

Leroy Quet, Jun 16 2007, Table of n, a(n) for n = 1..100

Mathematica

DivisorSigma[0, #]&/@Denominator[HarmonicNumber[Range[50]]] (* Harvey P. Dale, Mar 10 2019 *)

Crossrefs

Cf. A002805, A129568.

Sequence in context: A056763 A190071 A189498 * A064469 A057700 A337182

Adjacent sequences: A129564 A129565 A129566 * A129568 A129569 A129570

Keyword

nonn

Author

Leroy Quet, Apr 22 2007

Extensions

More terms from Max Alekseyev, Jun 16 2007

Status

approved