OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
Multiplicative with a(p^e) = 4 if p == 1 (mod 4) and 2 otherwise.
a(n) = 2^A086275(n).
EXAMPLE
a(2) = 2 since 2 = -i * (1 + i)^2, so it has 2 unitary divisors (up to associates): 1 and (1 + i)^2.
MATHEMATICA
f[p_, e_] := If[Abs[p] == 1, 1, 2]; a[n_] := Times @@ f @@@ FactorInteger[n, GaussianIntegers -> True]; Array[a, 100]
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Amiram Eldar, Feb 13 2020
STATUS
approved