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

Author

Jaroslav Krizek, Mar 07 2009, Apr 12 2009

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Cf. A007340, A000005, A000203, A001599.

Formula

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

Extensions

More terms from Amiram Eldar, Jul 09 2019