A082495 a(n) = (2^n - 1) mod n.

0, 1, 1, 3, 1, 3, 1, 7, 7, 3, 1, 3, 1, 3, 7, 15, 1, 9, 1, 15, 7, 3, 1, 15, 6, 3, 25, 15, 1, 3, 1, 31, 7, 3, 17, 27, 1, 3, 7, 15, 1, 21, 1, 15, 16, 3, 1, 15, 29, 23, 7, 15, 1, 27, 42, 31, 7, 3, 1, 15, 1, 3, 7, 63, 31, 63, 1, 15, 7, 43, 1, 63, 1, 3, 67, 15, 17, 63, 1, 15, 79, 3, 1, 63, 31, 3, 7, 79

Offset: 1

Author

Anonymous, Apr 28 2003

Keywords

• easy
• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A015910, A048298.

Cf. A000079, A062173.

Programs

Haskell

a082495 n = a015910 n + a048298 n - 1  -- Reinhard Zumkeller, Oct 17 2015

Mathematica

Table[Mod[2^m-1,m],{m,6!}] (* Vladimir Joseph Stephan Orlovsky, Feb 11 2010 *)

PARI

vector(80, n, (2^n-1) %n) \\ Michel Marcus, Jan 16 2015

Python

def A082495(n): return (m if (m:=pow(2,n,n)) else n)-1 # Chai Wah Wu, Dec 01 2022

Formula

a(n) = A015910(n) + A048298(n) - 1.