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A246901 a(n) is the n-th smallest prime p such that p+4n is also prime. 1
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 (list; graph; refs; listen; history; text; internal format)
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
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
KEYWORD
nonn
AUTHOR
Zak Seidov, Nov 16 2014
STATUS
approved

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Last modified March 19 06:32 EDT 2024. Contains 370953 sequences. (Running on oeis4.)