OFFSET

2,7

COMMENTS

LINKS

Amiram Eldar, Table of n, a(n) for n = 2..10000

FORMULA

a(A063948(n)) = 0.

EXAMPLE

a(8) = 2 since 8 is the sum of the proper unitary divisors of 10 (1 + 2 + 5) and 12 (1 + 3 + 4).

MATHEMATICA

us[1] = 0; us[n_] := Times @@ (1 + Power @@@ FactorInteger[n]) - n; m = 100; v = Table[0, {m}]; Do[u = us[k]; If[2 <= u <= m, v[[u]]++], {k, 1, m^2}]; Rest @ v

CROSSREFS

KEYWORD

nonn

AUTHOR

Amiram Eldar, Sep 05 2019

STATUS

approved