|
| |
|
|
A028785
|
|
Nonsquares mod 72.
|
|
1
|
|
|
|
2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 50, 51, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Table of n, a(n) for n=1..60.
|
|
|
EXAMPLE
|
x^2 = 27 mod 72 has no solutions, so 27 is in the sequence.
x^2 = 28 mod 72 has the following solutions: x = 10, x = 26, x = 46, x = 62. So 28 is not in the sequence.
|
|
|
MATHEMATICA
|
Complement[Range[71], PowerMod[Range[71], 2, 72]] (* Alonso del Arte, Jan 14 2017 *)
|
|
|
PROG
|
(Scala) (0 to 71).diff((1 to 72).map(n => (n * n) % 72)) // Alonso del Arte, Dec 24 2019
|
|
|
CROSSREFS
|
Cf. A010433.
Sequence in context: A028761 A028809 A337533 * A166546 A167759 A028812
Adjacent sequences: A028782 A028783 A028784 * A028786 A028787 A028788
|
|
|
KEYWORD
|
nonn,fini,full,easy
|
|
|
AUTHOR
|
N. J. A. Sloane
|
|
|
STATUS
|
approved
|
| |
|
|
