%I #8 Jan 17 2022 13:45:59
%S 5,11,31,59,71,89,179,181,191,199,229,251,269,311,331,379,389,401,419,
%T 421,449,499,509,521,599,619,631,641,661,691,709,719,751,829,839,859,
%U 881,911,929,971,991,1021,1039,1049,1061,1109,1171,1181,1259,1279,1291,1301,1321,1409,1439,1489,1499
%N Primes which are squares (mod 55).
%C 5, 11 and all primes congruent to 1, 4, 9, 14, 16, 26, 31, 34, 36, or 49 (mod 55). - _Robert Israel_, Jan 15 2016
%p S55:= {seq(x^2 mod 55, x=0..27)}:
%p select(t -> member(t mod 55, S55), [seq(ithprime(i),i=1..1000)]); # _Robert Israel_, Jan 15 2016
%t Join[{5,11},Select[Prime[Range[250]],MemberQ[{1,4,9,14,16,26,31,34,36,49},Mod[#,55]]&]] (* _Harvey P. Dale_, Jan 17 2022 *)
%o (PARI) select(p->issquare(Mod(p,55))&&isprime(p),[1..1500]) \\ It would be more efficient to select only among primes, replacing [1..1500] by primes([1,1500]), in which case the isprime() condition can be omitted from the selection function. But we wanted to provide a universally valid characteristic function in the 1st argument of select(). - _M. F. Hasler_, Jan 15 2016
%Y Cf. A106904 and adjacent sequences.
%Y Cf. A191036.
%K nonn
%O 1,1
%A _M. F. Hasler_, Jan 15 2016