A092419 - OEIS

A092419

Let k = n-th nonsquare = A000037(n); then a(n) = smallest prime p such that the Kronecker-Jacobi symbol K(k,p) = -1.

3, 2, 2, 7, 5, 3, 7, 2, 5, 2, 3, 13, 3, 5, 2, 3, 2, 5, 3, 7, 3, 2, 5, 2, 11, 7, 3, 5, 7, 2, 2, 3, 11, 7, 3, 5, 2, 3, 2, 11, 3, 5, 3, 2, 5, 2, 7, 7, 3, 5, 5, 2, 13, 2, 3, 5, 3, 7, 2, 3, 2, 13, 3, 5, 5, 3, 2, 7, 2, 5, 11, 3, 5, 2, 11, 2, 3, 5, 5, 3, 7, 2, 3, 2, 7, 3, 7, 5, 3, 2, 2, 5, 5, 3, 11, 11, 2, 5, 2, 3, 7

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OFFSET

1,1

COMMENTS

Maple calls K(k,p) the Legendre symbol.

The old entry with this sequence number was a duplicate of A024356.

REFERENCES

H. Cohen, A Course in Computational Number Theory, Springer, 1996 (p. 28 defines the Kronecker-Jacobi symbol).

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

MAPLE

with(numtheory); f:=proc(n) local M, i, j, k; M:=100000; for i from 1 to M do if legendre(n, ithprime(i)) = -1 then RETURN(ithprime(i)); fi; od; -1; end;

PROG

(PARI) a(n)=my(k=n+(sqrtint(4*n)+1)\2); forprime(p=2, , if(kronecker(k, p)<0, return(p))) \\ Charles R Greathouse IV, Aug 28 2016

CROSSREFS

Cf. A000037. Records: A067073, A070040. See A144294 for another version.

Sequence in context: A237270 A091264 A021760 * A293268 A020835 A244639

Adjacent sequences: A092416 A092417 A092418 * A092420 A092421 A092422

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Oct 16 2008, Oct 17 2008. Definition corrected Dec 03 2008.

STATUS

approved