A064596 Smallest nonunitary multiperfect number of index n; i.e., smallest k such that sigma(k) - usigma(k) = nk.

1, 24, 2520, 186076800

Offset

0,2

Comments

4.5*10^14 < a(4) <= 1081895452249824576000.

Links

Table of n, a(n) for n=0..3.

Mathematica

nusigma[ n_ ] := DivisorSigma[ 1, n ]-Times@@(1+Power@@#&/@FactorInteger[ n ]); a[ n_ ] := For[ k=1, True, k++, If[ nusigma[ k ]==n k, Return[ k ] ] ]

Crossrefs

Cf. A048146, A064591, A064592, A064593, A064594, A064595.

Sequence in context: A336864 A008977 A159392 * A217971 A296652 A092706

Adjacent sequences: A064593 A064594 A064595 * A064597 A064598 A064599

Keyword

nonn,hard,more

Author

Dean Hickerson, Sep 25 2001

Status

approved