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A028792 Nonsquares mod 79. 1

%I

%S 3,6,7,12,14,15,17,24,27,28,29,30,33,34,35,37,39,41,43,47,48,53,54,56,

%T 57,58,59,60,61,63,66,68,69,70,71,74,75,77,78

%N Nonsquares mod 79.

%F Legendre symbol (a(n)/79) = -1. - _Alonso del Arte_, Jan 15 2017

%e x^2 = 7 mod 79 has no solutions, hence 7 is in the sequence.

%e x^2 = 8 mod 79 has the solutions x = 18 and x = 61, so 8 is not in the sequence.

%t Complement[Range[78], PowerMod[Range[78], 2, 79]] (* _Alonso del Arte_, Jan 15 2017 *)

%o (PARI) isok(n) = (n < 79) && (kronecker(n, 79) == -1); \\ _Michel Marcus_, Jan 15 2017

%o (PARI) isok(n) = (n < 79) && (! issquare(Mod(n, 79))); \\ _Michel Marcus_, Jan 15 2017

%o (Scala) (0 to 78).diff((1 to 79).map(n => n * n % 79)) // _Alonso del Arte_, Jan 22 2020

%o (MAGMA) [n: n in [0..78] | not IsSquare(R! n) where R:= ResidueClassRing(79)]; // _Vincenzo Librandi_, Jan 23 2020

%Y Cf. A010440 (complement), A096013 (row 79).

%K nonn,fini,full,easy

%O 1,1

%A _N. J. A. Sloane_

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Last modified May 9 04:59 EDT 2021. Contains 343687 sequences. (Running on oeis4.)