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A246901 a(n) is the n-th smallest prime p such that p+4n is also prime.

%I A246901 #17 Jul 10 2015 19:23:08
%S A246901 3,5,11,31,41,23,73,131,47,97,149,83,229,167,89,337,311,167,307,293,
%T A246901 149,499,509,211,457,509,311,607,743,211,787,839,331,877,521,419,1171,
%U A246901 911,421,787,1289,419,1279,1103,433,1327,1361,619,1123,1103,617,1663,1721,661,1039,1553,739,2179,2111,599
%N A246901 a(n) is the n-th smallest prime p such that p+4n is also prime.
%C A246901 There is an array defined by: A(n,k) is the k-th smallest prime such that p+4*n is also prime (analog of A231608). It starts
%C A246901   3   7  13  19  37  43  67  79  97 103
%C A246901   3   5  11  23  29  53  59  71  89 101
%C A246901   5   7  11  17  19  29  31  41  47  59
%C A246901   3   7  13  31  37  43  67  73  97 151
%C A246901   3  11  17  23  41  47  53  59  83  89
%C A246901   5   7  13  17  19  23  29  37  43  47
%C A246901   3  13  19  31  43  61  73  79 103 109
%C A246901   5  11  29  41  47  71 107 131 149 167
%C A246901   5   7  11  17  23  31  37  43  47  53
%C A246901   3   7  13  19  31  43  61  67  73  97
%C A246901 a(n) = A(n,n) reads along the main diagonal of this array. - _R. J. Mathar_, Nov 19 2014
%H A246901 Zak Seidov, <a href="/A246901/b246901.txt">Table of n, a(n) for n = 1..1000</a>
%o A246901 (PARI) a(n) = nb=0; forprime(p=3,, if (isprime(p+4*n), nb++; if (nb==n, return (p)))); \\ _Michel Marcus_, Nov 16 2014
%Y A246901 Cf. A086505.
%K A246901 nonn
%O A246901 1,1
%A A246901 _Zak Seidov_, Nov 16 2014