A157850 Numbers k such that are harmonic means of divisors of harmonic (Ore) numbers (harmonic numbers is A001599) and equal to one of the divisors of this harmonic numbers.

1, 2, 5, 6, 8, 9, 11, 10, 15, 15, 14, 17, 24, 24, 21, 13, 19, 27, 25, 29, 26, 44, 44, 29, 46, 39, 46, 42, 47, 47, 35, 41, 60, 51, 37, 48, 45, 49, 50, 49, 53, 77, 86, 86, 51, 96, 75, 70, 80, 99, 110, 81, 84, 102, 82, 96, 114, 53, 108, 115, 105, 116, 91, 85, 105

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..847 (Calculated from the b-file at A007340)

Formula

a(n) = f(A007340(n)), where f(k) = k * tau(k)/sigma(k) = k * A000005(k)/A000203(k).

Example

a(3) = 5, because 5 is harmonic mean of divisors of A007340(3)=140 and also is divisor of 140.

Crossrefs

Cf. A007340, A000005, A000203, A001599.

Sequence in context: A299417 A047442 A005781 * A049636 A045573 A161152

Adjacent sequences: A157847 A157848 A157849 * A157851 A157852 A157853

Keyword

nonn

Author

Jaroslav Krizek, Mar 07 2009, Apr 12 2009

Extensions

More terms from Amiram Eldar, Jul 09 2019

Status

approved