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%I #23 Feb 06 2014 03:55:20
%S 0,0,1,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,
%T 0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,
%U 0,0,1,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0
%N Characteristic function of primes of form 4n+3 (1 if n is prime of form 4n+3, 0 otherwise).
%C Let M(n) denote the n X n matrix m(i,j)=0 if n divides ij-1, m(i,j) = 1 otherwise then det(M(n))=+1 if and only if n is prime ==3 (mod 4).
%C a(A002145(n)) = 1; a(A145395(n)) = 0. [From _Reinhard Zumkeller_, Oct 12 2008]
%C a(n) * A151763(n) = - a(n).
%H Reinhard Zumkeller, <a href="/A079261/b079261.txt">Table of n, a(n) for n = 1..10000</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%F a(n) = - A010051(n) * A011764(n+1). [_Reinhard Zumkeller_, Oct 06 2011]
%o (PARI) { a(n)=isprime(n)*if(n%4-3,0,1) }; vector(100,n,a(n))
%o (Haskell)
%o a079261 n = fromEnum $ n `mod` 4 == 3 && a010051 n == 1
%o -- _Reinhard Zumkeller_, Oct 06 2011
%Y Cf. A002145, A079260.
%Y Cf. A066490 (partial sums).
%K nonn
%O 1,1
%A _Benoit Cloitre_, Feb 04 2003
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