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 A091338 a(n) = (3/n), where (k/n) is the Kronecker symbol. 8
 1, -1, 0, 1, -1, 0, -1, -1, 0, 1, 1, 0, 1, 1, 0, 1, -1, 0, -1, -1, 0, -1, 1, 0, 1, -1, 0, -1, -1, 0, -1, -1, 0, 1, 1, 0, 1, 1, 0, 1, -1, 0, -1, 1, 0, -1, 1, 0, 1, -1, 0, 1, -1, 0, -1, 1, 0, 1, 1, 0, 1, 1, 0, 1, -1, 0, -1, -1, 0, -1, 1, 0, 1, -1, 0, -1, -1, 0, -1, -1, 0, 1, 1, 0, 1, 1, 0, -1, -1, 0, -1, 1, 0, -1, 1, 0, 1, -1, 0, 1, -1, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(2n+1) has period 6, i.e., if n == 1 (mod 2) then a(n+12) = a(n). A.H.M. Smeets, Jan 23 2018 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Jean-Paul Allouche, Leo Goldmakher, Mock characters and the Kronecker symbol, arXiv:1608.03957 [math.NT], 2016. Eric Weisstein's World of Mathematics, Kronecker Symbol FORMULA If n==0 (mod 3) a(n)=0; for p ==1 or 11 (mod 12) (i.e., p>3 in A038874), a(p)=+1; for p==2, 5 or 7 (mod 12) (i.e., p in A038875), a(p)=-1. - Benoit Cloitre, Jan 03 2004 From A.H.M. Smeets, Aug 01 2018: (Start) Conjecture: a(n) = 0 if and only if (n mod 3 = 0), a(n) = 1 if (n mod 12 = 1 or n mod 12 = 11 or n mod 48 = 4 or n mod 48 = 44), a(n) = -1 if (n mod 12 = 5 or n mod 12 = 7 or n mod 48 = 20 or n mod 48 = 28), a(2) = -1, a(12*n+10) = -a(12*n+2) and a(12*n+14) = a(12*n+10) for n >= 0, a(24*n+8) = -a(12*n+4) and a(24*n+16) = -a(12*n+4) for n >= 0. (End) From A.H.M. Smeets, Aug 01 2018: (Start) a(2*n+1) = 1 if and only if (n mod 6 = 0 or n mod 6 = 5), a(2*n+1) = -1 if and only if (n mod 6 = 2 or n mod 6 = 3), a(2*n+1) = 0 if and only if n mod 3 = 1, a(2*n) = -a(n). (End) MAPLE A091338 := proc(n)         numtheory[jacobi](3, n) ; end proc: # R. J. Mathar, Nov 03 2011 MATHEMATICA Table[KroneckerSymbol[3, n], {n, 1, 100}] (* Vincenzo Librandi, Aug 16 2016 *) PROG (PARI) a(n)=kronecker(3, n) (MAGMA) [KroneckerSymbol(3, n): n in [1..100]]; // Vincenzo Librandi, Aug 16 2016 CROSSREFS Sequence in context: A117441 A049347 A010892 * A016345 A016148 A016333 Adjacent sequences:  A091335 A091336 A091337 * A091339 A091340 A091341 KEYWORD sign,mult AUTHOR Eric W. Weisstein, Dec 30 2003 EXTENSIONS More terms from Benoit Cloitre, Jan 03 2004 STATUS approved

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Last modified January 26 23:05 EST 2020. Contains 331289 sequences. (Running on oeis4.)