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A066894

Numbers k such that prime(2*k) - prime(k) == 0 (mod k).

1, 2, 4, 6, 18, 42, 44, 49, 246, 257, 259, 272, 283, 294, 25284, 62648, 62664, 62673, 62700, 62701, 158706, 404835, 404859, 405119, 405448, 405451, 2630908, 2630929, 2631249, 2631303, 2631368, 2631414, 2631509, 2631517, 2631576, 2631666, 17405852, 44932936

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

prime(2*2) - prime(2) = 7 - 3 = 4 that is equal to 0 mod 2, so 2 is in the sequence.

PROG

(PARI) isok(n) = (prime(2*n)-prime(n)) % n == 0; \\ Michel Marcus, Nov 20 2013

CROSSREFS

Cf. A072473.

Sequence in context: A098853 A023149 A085146 * A233919 A111115 A195328