A066940 Numbers k such that gcd(prime(k+1) + 1, prime(k) + 1) = 2.

2, 3, 5, 6, 7, 10, 11, 12, 13, 17, 18, 20, 21, 24, 25, 26, 28, 29, 30, 33, 35, 36, 37, 41, 42, 43, 44, 45, 49, 50, 52, 53, 57, 58, 59, 60, 61, 64, 65, 66, 67, 68, 69, 70, 73, 74, 77, 78, 79, 81, 82, 83, 84, 87, 88, 89, 98, 99, 100, 101, 104, 105, 106, 109, 110, 111, 112, 113

Offset

1,1

Comments

Numbers k such that A063086(k) = 2. - Andrew Howroyd, Dec 10 2024

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Mathematica

Select[ Range[120], GCD[ Prime[ # + 1] + 1, Prime[ # ] + 1] == 2 & ]

Prog

(PARI) isok(k) = { gcd(prime(k+1) + 1, prime(k) + 1) == 2 } \\ Harry J. Smith, Apr 09 2010

Crossrefs

Cf. A063086, A066941, A066942, A066943, A066944, A067603, A067604.

Sequence in context: A107746 A024899 A114518 * A305318 A100118 A295389

Adjacent sequences: A066937 A066938 A066939 * A066941 A066942 A066943

Keyword

nonn

Author

Benoit Cloitre, Jan 24 2002

Extensions

Edited by Robert G. Wilson v, Feb 01 2002

Status

approved