A295308 Characteristic function for A066694: a(n) = 1 if n < phi(sigma(n)), 0 otherwise.

0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1

Links

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

Index entries for characteristic functions

Formula

a(n) = 1 if n < A062401(n), 0 otherwise.

Mathematica

Array[Boole[# < EulerPhi@ DivisorSigma[1, #]] &, 120] (* Michael De Vlieger, Nov 22 2017 *)

Prog

(PARI) a(n) = n < eulerphi(sigma(n)); \\ Michel Marcus, Nov 23 2017

Crossrefs

Cf. A000010, A000203, A062401, A066694, A295301, A295303, A295309.

Sequence in context: A024889 A368701 A101349 * A284954 A221151 A359474

Adjacent sequences: A295305 A295306 A295307 * A295309 A295310 A295311

Keyword

nonn

Author

Antti Karttunen, Nov 22 2017

Status

approved