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

1,2

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

Adjacent sequences: A066891 A066892 A066893 * A066895 A066896 A066897

Keyword

nonn

Author

Benoit Cloitre, Jan 24 2002

Extensions

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

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

Status

approved