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A269790 Primes p such that 2*p + 79 is a square. 1
73, 181, 2341, 4861, 6121, 9901, 12601, 18973, 20161, 26641, 47701, 51481, 59473, 61561, 68041, 79561, 81973, 84421, 94573, 110881, 157321, 185401, 192781, 207973, 231841, 244261, 248473, 270073, 292573, 335341, 365473, 440821, 446473, 452161, 475273 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes of the form 2*k^2 + 2*k - 39.

2*p + h is not verified if h is an odd prime that belongs to A055025 because (2*h-1)/2 is a multiple of 2.

LINKS

Table of n, a(n) for n=1..35.

EXAMPLE

a(1) = 73 because 2*73 + 79 = 225, which is a square.

MATHEMATICA

Select[Prime[Range[50000]], IntegerQ[Sqrt[2 # + 79]] &]

PROG

(MAGMA) [p: p in PrimesUpTo(600000) | IsSquare(2*p+79)];

(PARI) lista(nn) = {forprime(p=2, nn, if(issquare(2*p + 79), print1(p, ", "))); } \\ Altug Alkan, Mar 24 2016

(Python)

from sympy import isprime

from gmpy2 import is_square

for p in xrange(0, 1000000):

    if(is_square(2*p+79) and isprime(p)):print(p)

# Soumil Mandal, Apr 03 2016

CROSSREFS

Cf. A000040.

Subsequence of A002144, A045433, A061237, A068228.

Cf. similar sequences listed in A269784.

Sequence in context: A044786 A244774 A142550 * A142741 A088199 A140010

Adjacent sequences:  A269787 A269788 A269789 * A269791 A269792 A269793

KEYWORD

nonn

AUTHOR

Vincenzo Librandi, Mar 24 2016

STATUS

approved

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Last modified October 15 21:06 EDT 2018. Contains 316237 sequences. (Running on oeis4.)