A346468 a(n) = (n-1) / A346467(n).

0, 1, 1, 3, 1, 5, 1, 7, 2, 9, 1, 11, 1, 13, 7, 15, 1, 17, 1, 19, 1, 21, 1, 23, 2, 25, 13, 27, 1, 29, 1, 31, 2, 33, 17, 35, 1, 37, 19, 39, 1, 41, 1, 43, 1, 45, 1, 47, 1, 49, 5, 51, 1, 53, 3, 55, 2, 57, 1, 59, 1, 61, 31, 63, 4, 65, 1, 67, 17, 69, 1, 71, 1, 73, 37, 75, 19, 77, 1, 79, 1, 81, 1, 83, 1, 85, 43, 87, 1, 89

Offset: 1

Author

Antti Karttunen and Thomas Ordowski, Jul 22 2021

Keywords

• nonn

Comments

Numbers n such that a(n) = 1 are A248614(m)+1 for m > 0. These are all primes together with A317210. The set of these numbers has zero asymptotic density.

Links

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

Crossrefs

Cf. A002322, A027642, A248614, A317210, A346467.

Programs

Mathematica

{0}~Join~Array[#/CarmichaelLambda@ Denominator@ BernoulliB@ # &, 89] (* Michael De Vlieger, Nov 23 2021 *)

PARI

A346468(n) = if(1==n,0,my(m=1); fordiv(n-1,d,if(isprime(1+d),m = lcm(m,d))); ((n-1)/m));

Formula

a(n) = (n-1) / A346467(n).

a(n) = (n-1) / A002322(A027642(n-1)).