A295304 a(n) = +1 if sigma(phi(n)) > n, -1 if sigma(phi(n)) < n, and 0 if sigma(phi(n)) = n, where phi = A000010 and sigma = A000203.

0, -1, 0, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 0, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, 1, 0, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, 1, -1, 1, 1, 1, -1, 1, -1, 1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, 1, 1, 1, -1, 1, -1, 1, 1, 1, -1, 1, 1, 1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, 1

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Formula

a(n) = sign(A295302(n)) = sign(sigma(phi(n))-n), where phi = A000010 and sigma = A000203.

Mathematica

Array[Sign[DivisorSigma[1, EulerPhi[#]] - #] &, 100] (* Paolo Xausa, Feb 07 2025 *)

Prog

(PARI) A295304(n) = sign(sigma(eulerphi(n)) - n);

Crossrefs

Cf. A000010, A000203, A062402, A295302, A295303

Cf. A018784 (positions of 0's), A230201 (of -1's), A230203 (of +1's).

Sequence in context: A072165 A358224 A072608 * A171386 A189816 A342000

Adjacent sequences: A295301 A295302 A295303 * A295305 A295306 A295307

Keyword

sign

Author

Antti Karttunen, Nov 21 2017

Status

approved