A151763 - OEIS

A151763

If n is a prime == 1 mod 4 then a(n) = 1, if n is a prime == 3 mod 4 then a(n) = -1, otherwise a(n) = 0.

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

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OFFSET

1,1

COMMENTS

a(A002145(n)) = -1; a(A065090(n)) = 0; a(A002144(n)) = 1. [Reinhard Zumkeller, Oct 06 2011]

LINKS

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

N. Katz, Lang-Trotter revisited, Bull. Amer. Math. Soc., 46 (2009), 413-457.

FORMULA

a(n) = (2 - n mod 4) * A010051(n).

MAPLE

a:= proc(n) if n::odd and isprime(n) then 2 - (n mod 4) else 0 fi end proc: