A029854 a(n) = gcd(prime(n)+prime(n+1), prime(n+1)+prime(n+2)).

1, 4, 6, 6, 6, 6, 6, 2, 4, 4, 2, 6, 6, 10, 4, 8, 8, 2, 6, 8, 2, 2, 2, 6, 6, 6, 6, 6, 6, 6, 2, 4, 12, 12, 4, 4, 10, 10, 4, 8, 12, 12, 6, 6, 2, 2, 2, 6, 6, 2, 8, 12, 4, 4, 4, 4, 4, 2, 6, 12, 24, 6, 6, 6, 18, 4, 4, 12, 6, 2, 2, 2, 4, 2, 2, 2, 6, 6, 18, 12, 12, 12, 8

Offset

1,2

Comments

a(n) = gcd(A001043(n), A001043(n+1)).

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Example

a(20) = gcd(71+73, 73+79) = gcd(144,152) = 8*gcd(18,19) = 8.

Mathematica

GCD[#[[1]]+#[[2]], #[[2]]+#[[3]]]&/@Partition[Prime[Range[90]], 3, 1] (* Harvey P. Dale, Mar 06 2014 *)

Prog

(PARI) a(n) = gcd(prime(n)+prime(n+1), prime(n+1)+prime(n+2)); \\ Michel Marcus, Aug 04 2013
(Haskell)
a029854 n = a029854_list !! (n-1)
a029854_list = zipWith gcd a001043_list $ tail a001043_list
-- Reinhard Zumkeller, Aug 08 2013

Crossrefs

Sequence in context: A270541 A046262 A147862 * A329502 A141328 A322345

Adjacent sequences: A029851 A029852 A029853 * A029855 A029856 A029857

Keyword

nonn

Author

Reinhard Zumkeller, Feb 14 2002

Status

approved