A346468 - OEIS

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

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OFFSET

1,4

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

FORMULA

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

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

MATHEMATICA

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

PROG

(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));

CROSSREFS

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

Sequence in context: A328478 A093411 A147088 * A340083 A339667 A322993

Adjacent sequences: A346465 A346466 A346467 * A346469 A346470 A346471

KEYWORD

nonn

AUTHOR

Antti Karttunen and Thomas Ordowski, Jul 22 2021

STATUS

approved