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A028755 Nonsquares mod 42. 1
2, 3, 5, 6, 8, 10, 11, 12, 13, 14, 17, 19, 20, 23, 24, 26, 27, 29, 31, 32, 33, 34, 35, 38, 40, 41 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..26.

MATHEMATICA

Complement[Range[0, 41], PowerMod[Range[42], 2, 42]] (* Alonso del Arte, Dec 21 2019 *)

PROG

(PARI) for(k=0, 42, if(!issquare(Mod(k, 42)), print1(k, ", "))) \\ Hugo Pfoertner, Dec 02 2019

(Scala) (0 to 41).diff((1 to 42).map(n => (n * n) % 42)) // Alonso del Arte, Dec 21 2019

CROSSREFS

Cf. A010403.

Sequence in context: A283513 A028776 A028734 * A187897 A187319 A095976

Adjacent sequences:  A028752 A028753 A028754 * A028756 A028757 A028758

KEYWORD

nonn,fini,full,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

Incorrect term 21 removed by Alonso del Arte, Dec 01 2019

STATUS

approved

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Last modified July 4 05:54 EDT 2020. Contains 335444 sequences. (Running on oeis4.)