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from sympy.ntheory.primetest import mobius, integer_nthroot
from sympy import mobius
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return udivisor_sigma(m) # Chai Wah Wu, Aug 05 2024
(Python)
from sympy.ntheory.factor_ import udivisor_sigma
from sympy.ntheory.primetest import integer_nthroot
from sympy import mobius
def A366537(n):
def f(x): return n+x-sum(mobius(k)*(x//k**3) for k in range(1, integer_nthroot(x, 3)[0]+1))
m, k = n, f(n)
while m != k:
m, k = k, f(k)
return udivisor_sigma(m) # Chai Wah Wu, Aug 05 2024
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Amiram Eldar, <a href="/A366537/b366537_1.txt">Table of n, a(n) for n = 1..10000</a>
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