|
%I #53 Sep 08 2022 08:46:14
%S 2,5,13,37,53,173,277,317,557,613,733,797,1237,1493,1973,2293,3533,
%T 4253,4877,5717,9293,9973,12157,12413,14557,16573,17477,19037,20333,
%U 22013,23053,26317,26693,30197,32237,32653,33493,37853,40597,44893,50957,53597,54133
%N Primes of the form k*(k+2)/3 - 3, k>2.
%C Primes p such that 3*p + 10 is a square.
%p a(1) = 2 because 2*3 + 10 = 16, which is a square.
%p a(1) = 2 because 3*(3 + 2)/3 - 3 = 2 is prime.
%t Select[Table[(k (k + 2))/3 - 3, {k, 2, 450}], PrimeQ]
%o (Magma) [a: k in [2..250] | IsPrime(a) where a is k*(k+2) div 3 - 3 ]; /* or */ [p: p in PrimesUpTo(60000) | IsSquare(3*p+10)];
%o (PARI) forprime(p=2, 1e5, if(issquare(3*p+10), print1(p , ", "))) \\ _Altug Alkan_, Dec 05 2015
%Y Cf. A162307, A201716.
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Dec 05 2015
|
