A066984 a(n) = gcd(prime(n+1) - 1, prime(n) + 1).

1, 4, 6, 2, 12, 2, 18, 2, 4, 30, 4, 2, 42, 2, 4, 2, 60, 2, 2, 72, 2, 2, 4, 6, 2, 102, 2, 108, 2, 6, 2, 4, 138, 4, 150, 4, 2, 2, 4, 2, 180, 2, 192, 2, 198, 10, 2, 2, 228, 2, 2, 240, 2, 4, 2, 4, 270, 4, 2, 282, 4, 6, 2, 312, 2, 6, 4, 2, 348, 2, 2, 6, 4, 2, 2, 4, 6, 2, 6, 2, 420, 2, 432, 2, 2

Offset

1,2

Links

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

Mathematica

GCD[#[[1]]+1, #[[2]]-1]&/@Partition[Prime[Range[90]], 2, 1] (* Harvey P. Dale, May 16 2021 *)

Prog

(PARI) a(n) = { gcd(prime(n+1) - 1, prime(n) + 1) } \\ Harry J. Smith, Apr 15 2010

Crossrefs

Sequence in context: A366952 A256508 A059030 * A364724 A241341 A085595

Adjacent sequences: A066981 A066982 A066983 * A066985 A066986 A066987

Keyword

nonn

Author

Benoit Cloitre, Jan 27 2002

Status

approved