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
KEYWORD
fini,full,easy,nonn
AUTHOR
T. D. Noe, Jan 22 2008
STATUS
approved