A058384 - OEIS

A058384

Largest power of 2 which is a divisor of p(n)-1, where p(n) = n-th prime.

1, 2, 4, 2, 2, 4, 16, 2, 2, 4, 2, 4, 8, 2, 2, 4, 2, 4, 2, 2, 8, 2, 2, 8, 32, 4, 2, 2, 4, 16, 2, 2, 8, 2, 4, 2, 4, 2, 2, 4, 2, 4, 2, 64, 4, 2, 2, 2, 2, 4, 8, 2, 16, 2, 256, 2, 4, 2, 4, 8, 2, 4, 2, 2, 8, 4, 2, 16, 2, 4, 32, 2, 2, 4, 2, 2, 4, 4, 16, 8, 2, 4, 2, 16, 2, 2, 64, 8, 4, 2, 2, 2, 2, 2, 2, 2, 4, 8

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OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A006519(A006093(n)). - Amiram Eldar, Sep 23 2019

EXAMPLE

n=25, p(25) - 1 = 97 - 1 = 96 = 32 * 3, so a(25) = 32.

MATHEMATICA

2^IntegerExponent[#, 2]&/@(Prime[Range[100]]-1) (* Harvey P. Dale, Jan 17 2013 *)

CROSSREFS