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A079260
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Characteristic function of primes of form 4n+1 (1 if n is prime of form 4n+1, 0 otherwise).
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11
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0, 0, 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, 1, 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, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0
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OFFSET
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1,1
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COMMENTS
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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 =2 or if n is prime ==1 (mod 4).
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LINKS
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MATHEMATICA
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Table[If[PrimeQ[n]&&IntegerQ[(n-1)/4], 1, 0], {n, 120}] (* Harvey P. Dale, Jul 14 2015 *)
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PROG
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(PARI) { a(n)=if(n%4==1, isprime(n)) }; vector(100, n, a(n))
(Haskell)
a079260 n = fromEnum $ n `mod` 4 == 1 && a010051 n == 1
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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