OFFSET
1,1
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..28 (terms below 10^12, from David Moews's site).
David Moews, Perfect, amicable and sociable numbers
J. O. M. Pedersen, Tables of Aliquot Cycles
EXAMPLE
172622505 is in the sequence since it is the lesser of the amicable pair (172622505, 175742294): usigma(172622505) = usigma(175742294) = 348364800 = 172622505 + 175742294 + 1.
MATHEMATICA
us[n_] := Times @@ (1 + Power @@@ FactorInteger[n]) - n; s={}; Do[m = us[n] - 1; If[m > n && us[m] == n + 1, AppendTo[s, n]], {n, 1, 10^9}]; s
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Mar 14 2019
STATUS
approved