1,1

The divisors of a perfect number N=2^(p-1)*M(p) (=A000396), {with associated Mersenne prime M(p)=2^p -1 (=A000668)}, has harmonic mean N*tau(N)/sigma(N) = p (=A000043).

a(n)= m*tau(m)/sigma(m), where m=A090945(n), tau=A000005 and sigma=A000203

Sequence in context: A099149 A057854 A033266 this_sequence A120174 A047439 A095763

Adjacent sequences: A102405 A102406 A102407 this_sequence A102409 A102410 A102411

nonn

Lekraj Beedassy (blekraj(AT)yahoo.com), Jan 07 2005