%I #30 Sep 08 2022 08:46:01
%S 5,17,53,113,197,593,773,977,1733,2357,4337,5297,5813,6353,6917,8117,
%T 8753,9413,13877,16433,17333,18257,20177,22193,26513,27653,28817,
%U 33713,38993,41777,44657,46133,49157,60497,62213,65717,69317,71153
%N Primes of the form 3n^2 + 5.
%C Starting at a(3) all primes in this sequence are of the form (2*k+1)*(2*k+3)+(2*k+3)*(2*k+5)+(2*k+5)*(2*k+7) = 12*k^2 + 48*k + 53 for some k >= 0. For example a(5) = 5*7 + 7*9 + 9*11 = 197. - _J. M. Bergot_, Nov 03 2014
%H Vincenzo Librandi, <a href="/A201478/b201478.txt">Table of n, a(n) for n = 1..5000</a>
%t Select[Table[3n^2 + 5, {n, 0, 700}], PrimeQ]
%o (Magma) [a: n in [0..400] | IsPrime(a) where a is 3*n^2+5];
%o (PARI) select(isprime, vector(100,n,3*n^2+5)) \\ _Charles R Greathouse IV_, Nov 05 2014
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Dec 02 2011