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

Offset: 1

Author

Benoit Cloitre, Jan 24 2002

Keywords

• nonn

Examples

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

Crossrefs

Cf. A072473.

Programs

PARI

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

Extensions

a(15)-a(20) from Michel Marcus, Nov 20 2013

a(21)-a(38) from Donovan Johnson, Nov 20 2013