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A028767 Nonsquares mod 54. 1
2, 3, 5, 6, 8, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24, 26, 29, 30, 32, 33, 35, 38, 39, 41, 42, 44, 45, 47, 48, 50, 51, 53 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..32.

MATHEMATICA

Complement[Range[0, 53], PowerMod[Range[54], 2, 54]] (* Alonso del Arte, Dec 27 2019 *)

PROG

(Scala) (0 to 53).diff((1 to 54).map(n => (n * n) % 54)) // Alonso del Arte, Dec 27 2019

(MAGMA) [ n: n in [0..53] | not IsSquare(R! n) where R:= ResidueClassRing(54)]; // Vincenzo Librandi, Dec 28 2019

CROSSREFS

Cf. A010415.

Sequence in context: A028740 A028794 A028966 * A268226 A138529 A266409

Adjacent sequences:  A028764 A028765 A028766 * A028768 A028769 A028770

KEYWORD

nonn,fini,full,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified June 24 00:22 EDT 2021. Contains 345403 sequences. (Running on oeis4.)