A267478 - OEIS

A267478

Primes which are squares (mod 55).

5, 11, 31, 59, 71, 89, 179, 181, 191, 199, 229, 251, 269, 311, 331, 379, 389, 401, 419, 421, 449, 499, 509, 521, 599, 619, 631, 641, 661, 691, 709, 719, 751, 829, 839, 859, 881, 911, 929, 971, 991, 1021, 1039, 1049, 1061, 1109, 1171, 1181, 1259, 1279, 1291, 1301, 1321, 1409, 1439, 1489, 1499

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OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..57.

MAPLE

S55:= {seq(x^2 mod 55, x=0..27)}:

select(t -> member(t mod 55, S55), [seq(ithprime(i), i=1..1000)]); # Robert Israel, Jan 15 2016

MATHEMATICA

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 *)

PROG

(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

CROSSREFS

Cf. A106904 and adjacent sequences.

Cf. A191036.

Sequence in context: A371670 A105910 A023259 * A280081 A057470 A038580

Adjacent sequences: A267475 A267476 A267477 * A267479 A267480 A267481

KEYWORD

nonn

AUTHOR

M. F. Hasler, Jan 15 2016

STATUS

approved