OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); usigma[1] = 1; seq[max_] := TakeWhile[Union[Array[usigma, max]], # <= max &]; seq[160] (* Amiram Eldar, Jul 22 2024 *)
PROG
(PARI) usigma(n) = {my(f = factor(n)); prod(i = 1, #f~, 1 + f[i, 1]^f[i, 2]); }
lista(nmax) = Set(select(x -> x <= nmax, vector(nmax, i, usigma(i)))); \\ Amiram Eldar, Jul 22 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Sep 05 2001
STATUS
approved