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A080403

Numbers n such that both A000203(n) and A001157(n) are squarefree: sum of divisors and squares of divisors of n are squarefree.

1, 2, 4, 5, 8, 9, 13, 16, 18, 20, 25, 29, 37, 49, 50, 61, 64, 72, 73, 80, 101, 109, 113, 116, 117, 121, 122, 128, 137, 144, 148, 169, 173, 181, 200, 208, 218, 229, 242, 244, 261, 277, 281, 289, 292, 313, 317, 320, 325, 333, 353, 362, 373, 389, 397, 401, 404, 409

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OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

Do[s1=MoebiusMu[DivisorSigma[1, n]]; s2=MoebiusMu[DivisorSigma[2, n]]; If[ !Equal[s1, 0]&&!Equal[s2, 0], Print[n]], {n, 1, 1000}]

CROSSREFS

Cf. A001157, A000203, A065300, A080401, A080402.

Sequence in context: A385524 A372953 A065300 * A280050 A360772 A271392

Adjacent sequences: A080400 A080401 A080402 * A080404 A080405 A080406

KEYWORD

easy,nonn

AUTHOR

Labos Elemer, Mar 19 2003

STATUS

approved

URL: https://oeis.org/A080403

⇱ A080403 - OEIS