OFFSET

1,1

EXAMPLE

Since 10 is not a perfect square, and there are no solutions in integers to x^2 = 10 mod 19, 10 is in the sequence.

Although 11 is not a perfect square either, there are solutions in integers to x^2 = 11 mod 19, such as x = 7, x = 12. Hence 11 is not in the sequence.

MATHEMATICA

Select[Range[18], JacobiSymbol[#, 19] != 1 &] (* Alonso del Arte, Nov 19 2019 *)

PROG

(Scala) val squaresMod19 = (0 to 18).map(n => n * n).map(_ % 19)

(0 to 18).diff(squaresMod19) // Alonso del Arte, Nov 19 2019

CROSSREFS

KEYWORD

nonn,fini,full

AUTHOR

STATUS

approved