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1,1
Table of n, a(n) for n=1..66.
Complement[Range[0, 89], PowerMod[Range[90], 2, 90]] (* Alonso del Arte, Jan 03 2020 *)
(Scala) (0 to 89).diff((1 to 90).map(n => n * n % 90)) // Alonso del Arte, Jan 03 2020
Cf. A010451.
Sequence in context: A219255 A025501 A028758 * A050942 A096600 A122686
Adjacent sequences: A028800 A028801 A028802 * A028804 A028805 A028806
nonn,fini,full,easy
N. J. A. Sloane
approved