1,3

usigma(m) is the sum of unitary divisors of m, A034448.

Daniel Suteu, Table of n, a(n) for n = 1..10000

a(12)=11 because the unitary divisors of 11 are 1,11; they sum to 12.

Cf. A034444, A034448, A051444, A057637, A063972.

Sequence in context: A224892 A265517 A063972 * A126441 A004181 A080744

Adjacent sequences: A063970 A063971 A063972 * A063974 A063975 A063976

nonn

Labos Elemer, Sep 05 2001

Corrected by Don Reble, May 14 2006

approved