A106743 a(n) = -1 iff n is prime, a(n) = 1 iff n is not squarefree, otherwise (n is nonprime and squarefree) a(n) = 0.

0, -1, -1, 1, -1, 0, -1, 1, 1, 0, -1, 1, -1, 0, 0, 1, -1, 1, -1, 1, 0, 0, -1, 1, 1, 0, 1, 1, -1, 0, -1, 1, 0, 0, 0, 1, -1, 0, 0, 1, -1, 0, -1, 1, 1, 0, -1, 1, 1, 1, 0, 1, -1, 1, 0, 1, 0, 0, -1, 1, -1, 0, 1, 1, 0, 0, -1, 1, 0, 0, -1, 1, -1, 0, 1, 1, 0, 0, -1, 1, 1, 0, -1, 1, 0, 0, 0, 1, -1, 1, 0, 1, 0, 0, 0, 1, -1, 1, 1, 1, -1, 0, -1, 1, 0

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Formula

a(n) = 1 - 0^(A001222(n)-A001221(n)) - 0^(A001222(n)-1), for n>1. - Reinhard Zumkeller, May 23 2005

Mathematica

Table[Which[PrimeQ[n], -1, SquareFreeQ[n], 0, True, 1], {n, 110}] (* Harvey P. Dale, Aug 30 2015 *)

Prog

(PARI) for(n=1, 105, print1(if(!issquarefree(n), 1, if(isprime(n), -1, 0)), ", "))

Crossrefs

Cf. A000040 (prime), A013929 (not squarefree), A000469 (nonprime and squarefree), A082926.

Sequence in context: A069513 A092248 A354920 * A284944 A284674 A225181

Adjacent sequences: A106740 A106741 A106742 * A106744 A106745 A106746

Keyword

sign

Author

Giovanni Teofilatto, May 16 2005

Extensions

Edited and extended by Klaus Brockhaus, May 16 2005

Status

approved