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A355928
Squarefree part of the sum of divisors of n.
3
1, 3, 1, 7, 6, 3, 2, 15, 13, 2, 3, 7, 14, 6, 6, 31, 2, 39, 5, 42, 2, 1, 6, 15, 31, 42, 10, 14, 30, 2, 2, 7, 3, 6, 3, 91, 38, 15, 14, 10, 42, 6, 11, 21, 78, 2, 3, 31, 57, 93, 2, 2, 6, 30, 2, 30, 5, 10, 15, 42, 62, 6, 26, 127, 21, 1, 17, 14, 6, 1, 2, 195, 74, 114, 31, 35, 6, 42, 5, 186, 1, 14, 21, 14, 3, 33, 30, 5, 10
OFFSET
1,2
COMMENTS
Not multiplicative.
FORMULA
a(n) = A007913(A000203(n)).
a(n) = A355929(n) + A007913(n).
PROG
(PARI) A355928(n) = core(sigma(n));
(Python)
from sympy.ntheory.factor_ import core, divisor_sigma
def A355928(n): return core(divisor_sigma(n)) # Chai Wah Wu, Jul 28 2022
CROSSREFS
Cf. A000203, A007913, A006532 (positions of 1's), A355929.
Cf. also A080398.
Sequence in context: A054458 A110168 A323663 * A205298 A046913 A118228
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 24 2022
STATUS
approved