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A269787 Primes p such that 2*p + 43 is a square.

%I A269787 #20 Sep 08 2022 08:46:16
%S A269787 3,19,199,523,739,991,1279,2791,3259,6823,9091,12619,13591,15643,
%T A269787 17839,32491,34039,37243,40591,63703,68059,72559,79579,86923,89443,
%U A269787 105319,110899,137791,144163,153991,160723,171091,178183,192799,196543,200323,211879,219763
%N A269787 Primes p such that 2*p + 43 is a square.
%C A269787 Primes of the form 2*k^2 + 2*k - 21.
%t A269787 Select[Prime[Range[25000]], IntegerQ[Sqrt[2 # + 43]] &]
%o A269787 (Magma) [p: p in PrimesUpTo(300000) | IsSquare(2*p + 43)];
%o A269787 (PARI) lista(nn) = forprime(p=2, nn, if (issquare(2*p+43), print1(p, ", "))); \\ _Michel Marcus_, Mar 22 2016
%o A269787 (Python)
%o A269787 from gmpy2 import is_prime,is_square
%o A269787 for p in range(3,10**6,2):
%o A269787     if(not is_square(2*p+43)):continue
%o A269787     elif(is_prime(p)):print(p)
%o A269787 # _Soumil Mandal_, Apr 07 2016
%Y A269787 Cf. A000040.
%Y A269787 Subsequence of A002145, A045409.
%Y A269787 Cf. similar sequences listed in A269784.
%K A269787 nonn
%O A269787 1,1
%A A269787 _Vincenzo Librandi_, Mar 22 2016