A353808 a(n) = 1 if A187730(n) < A049559(n), otherwise 0. Here A187730(n) and A049559(n) are the greatest common divisors between Carmichael lambda(n) and n-1, and between Euler phi(n) and n-1, respectively.

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

Offset

1

Links

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

Index entries for characteristic functions

Formula

a(n) = [A353801(n) > 1], where [ ] is the Iverson bracket.

a(n) >= A353483(n). [See Thomas Ordowski's Mar 30 2017 comment in A280262]

Mathematica

a[n_] := If[GCD[n - 1, CarmichaelLambda[n]] < GCD[n - 1, EulerPhi[n]], 1, 0]; Array[a, 100] (* Amiram Eldar, May 13 2022 *)

Prog

(PARI)
A049559(n) = gcd(n-1, eulerphi(n));
A187730(n) = gcd(lcm(znstar(n)[2]), n-1); \\ From A187730
A353808(n) = (A187730(n) < A049559(n));

Crossrefs

Characteristic function of A280262.

Cf. A000010, A002322, A049559, A187730, A353483, A353801.

Sequence in context: A355816 A353483 A353809 * A353482 A336355 A324731

Adjacent sequences: A353805 A353806 A353807 * A353809 A353810 A353811

Keyword

nonn

Author

Antti Karttunen, May 13 2022

Status

approved