A355928 Squarefree part of the sum of divisors of n.

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.

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Index entries for sequences related to sigma(n)

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

Adjacent sequences: A355925 A355926 A355927 * A355929 A355930 A355931

Keyword

nonn

Author

Antti Karttunen, Jul 24 2022

Status

approved