A063086 a(n) = gcd(1 + prime(n+1), 1 + prime(n)).

1, 2, 2, 4, 2, 2, 2, 4, 6, 2, 2, 2, 2, 4, 6, 6, 2, 2, 4, 2, 2, 4, 6, 2, 2, 2, 4, 2, 2, 2, 4, 6, 2, 10, 2, 2, 2, 4, 6, 6, 2, 2, 2, 2, 2, 4, 4, 4, 2, 2, 6, 2, 2, 6, 6, 6, 2, 2, 2, 2, 2, 14, 4, 2, 2, 2, 2, 2, 2, 2, 6, 8, 2, 2, 4, 6, 2, 2, 2, 10, 2, 2, 2, 2, 4, 6, 2, 2, 2, 4, 12, 8, 4, 4, 4, 6, 6, 2, 2, 2, 2, 6

Offset: 1

Author

Labos Elemer, Aug 06 2001

Keywords

• easy
• nonn

Examples

			n=34: gcd(1 + 139, 1 + 149) = 10 = a(34).
		

Links

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

Crossrefs

Cf. A058263.

Programs

Mathematica

GCD[First[#]+1,Last[#]+1]&/@ Partition[Prime[Range[110]],2,1] (* Harvey P. Dale, May 02 2012 *)

PARI

a(n)={gcd(1 + prime(n+1), 1 + prime(n))} \\ Harry J. Smith, Aug 17 2009