login
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
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
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Mar 07 2009, Apr 12 2009
EXTENSIONS
More terms from Amiram Eldar, Jul 09 2019
STATUS
approved