A306224 - OEIS

A306224

a(n) is the smallest prime p such that -n is not a square mod p.

3, 5, 5, 3, 11, 13, 3, 5, 7, 3, 7, 5, 3, 11, 7, 3, 5, 5, 3, 11, 13, 3, 5, 13, 3, 11, 5, 3, 7, 7, 3, 5, 5, 3, 19, 7, 3, 5, 7, 3, 13, 5, 3, 7, 11, 3, 5, 5, 3, 7, 7, 3, 5, 13, 3, 11, 5, 3, 11, 7, 3, 5, 5, 3, 7, 19, 3, 5, 11, 3, 7, 5, 3, 7, 11, 3, 5, 5, 3, 11, 7, 3, 5, 13, 3, 7, 5

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OFFSET

1,1

COMMENTS

a(n) is the smallest odd prime p such that Kronecker(-n,p) = -1.

A companion sequence to A144294.

Conjecture: lim sup log(a(n))/log(n) = 0.

LINKS

Table of n, a(n) for n=1..87.

FORMULA

a(n) = 3 if and only if n == 1 (mod 3).

a(n) = 5 if and only if n == 2, 3, 8, 12 (mod 15).