A136803 Squares mod 257.

0, 1, 2, 4, 8, 9, 11, 13, 15, 16, 17, 18, 21, 22, 23, 25, 26, 29, 30, 31, 32, 34, 35, 36, 42, 44, 46, 49, 50, 52, 57, 58, 59, 60, 61, 62, 64, 67, 68, 70, 72, 73, 79, 81, 84, 88, 89, 92, 95, 98, 99, 100, 104, 111, 113, 114, 116, 117, 118, 120, 121, 122, 123, 124

Offset

1,3

Comments

Because 257 is a Fermat prime, the complement of this set, A136804, is the set of primitive roots (mod 257).

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..129 (full sequence)

OEIS Wiki, Index to sequences related to squares

Formula

a(n) + a(131-n) = 257 for n>1.

Maple

A136803 := {}: for n from 0 to 256 do A136803 := A136803 union {n^2 mod 257}: od: op(sort(convert(A136803, list))); # Nathaniel Johnston, Jun 23 2011

Mathematica

p = 257; Select[Range[0, p - 1], JacobiSymbol[ #, p] == 1 &] (* T. D. Noe *)
Table[Mod[n^2, 257], {n, 0, 65}] (* Alonso del Arte, Feb 14 2013 *)

Prog

(PARI) for (n=0, 256, if (issquare(Mod(n, 257)), print1(n, ", "))) \\ Michel Marcus, Mar 12 2017
(PARI) A136803=Set([k^2 | k <- [0..256]]%257); \\ M. F. Hasler, Nov 15 2017
(PARI) lift(select(issquare, Mod([0..256], 257))) \\ M. F. Hasler, Nov 15 2017

Crossrefs

Cf. A136804 (nonsquares mod 257), A136805 and A136806 (squares/nonsquares mod 65537).

Sequence in context: A325942 A325944 A165569 * A035268 A035241 A034036

Adjacent sequences: A136800 A136801 A136802 * A136804 A136805 A136806

Keyword

fini,full,easy,nonn

Author

T. D. Noe, Jan 22 2008

Status

approved