A007423 a(n) = mu(n) + 1, where mu is the Moebius function.

2, 0, 0, 1, 0, 2, 0, 1, 1, 2, 0, 1, 0, 2, 2, 1, 0, 1, 0, 1, 2, 2, 0, 1, 1, 2, 1, 1, 0, 0, 0, 1, 2, 2, 2, 1, 0, 2, 2, 1, 0, 0, 0, 1, 1, 2, 0, 1, 1, 1, 2, 1, 0, 1, 2, 1, 2, 2, 0, 1, 0, 2, 1, 1, 2, 0, 0, 1, 2, 0, 0, 1, 0, 2, 1, 1, 2, 0, 0, 1, 1, 2, 0, 1, 2, 2, 2, 1, 0, 1, 2, 1, 2, 2, 2, 1, 0, 1, 1, 1

Offset: 1

Author

N. J. A. Sloane

Keywords

• easy
• nonn
• nice

References

• G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 234.
• K. Ireland and M. Rosen, A Classical Introduction to Modern Number Theory. Springer-Verlag, NY, 1982, p. 19.
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

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

Crossrefs

Cf. A008683 (mu).

Programs

Haskell

a007423 = (+ 1) . a008683  -- Reinhard Zumkeller, Jul 30 2014

Maple

with(numtheory); A007423:=n->mobius(n)+1; seq(A007423(k), k=1..100); # Wesley Ivan Hurt, Oct 24 2013

Mathematica

MoebiusMu[Range[100]]+1 (* Harvey P. Dale, Nov 08 2011 *)

PARI

a(n)=moebius(n)+1 \\ Charles R Greathouse IV, Feb 25 2018

Formula

a(n) = abs(a(n)).