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

3, 5, 11, 31, 41, 23, 73, 131, 47, 97, 149, 83, 229, 167, 89, 337, 311, 167, 307, 293, 149, 499, 509, 211, 457, 509, 311, 607, 743, 211, 787, 839, 331, 877, 521, 419, 1171, 911, 421, 787, 1289, 419, 1279, 1103, 433, 1327, 1361, 619, 1123, 1103, 617, 1663, 1721, 661, 1039, 1553, 739, 2179, 2111, 599

Offset

1,1

Comments

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

3 7 13 19 37 43 67 79 97 103

3 5 11 23 29 53 59 71 89 101

5 7 11 17 19 29 31 41 47 59

3 7 13 31 37 43 67 73 97 151

3 11 17 23 41 47 53 59 83 89

5 7 13 17 19 23 29 37 43 47

3 13 19 31 43 61 73 79 103 109

5 11 29 41 47 71 107 131 149 167

5 7 11 17 23 31 37 43 47 53

3 7 13 19 31 43 61 67 73 97

a(n) = A(n,n) reads along the main diagonal of this array. - R. J. Mathar, Nov 19 2014

Links

Zak Seidov, Table of n, a(n) for n = 1..1000

Prog

(PARI) a(n) = nb=0; forprime(p=3, , if (isprime(p+4*n), nb++; if (nb==n, return (p)))); \\ Michel Marcus, Nov 16 2014

Crossrefs

Cf. A086505.

Sequence in context: A108259 A093933 A165572 * A236568 A095184 A048235

Adjacent sequences: A246898 A246899 A246900 * A246902 A246903 A246904

Keyword

nonn

Author

Zak Seidov, Nov 16 2014

Status

approved