A227288 Greatest common divisor of consecutive terms in A227113.

1, 2, 1, 3, 1, 5, 1, 7, 2, 4, 3, 3, 1, 11, 1, 13, 2, 2, 1, 17, 1, 19, 2, 4, 3, 3, 1, 23, 1, 5, 2, 4, 1, 29, 1, 31, 1, 3, 1, 5, 1, 37, 1, 3, 1, 41, 1, 43, 2, 4, 3, 5, 1, 47, 1, 7, 1, 3, 2, 4, 1, 53, 1, 5, 1, 3, 1, 59, 1, 61, 2, 2, 1, 67, 2, 2, 1, 3, 1, 71, 1

Offset: 1

Author

Reinhard Zumkeller, Jul 05 2013

Keywords

• nonn

Comments

a(n) = GCD(A227113(n),A227113(n+1));

a(2*n) > 1 by definition of A227113;

9 is the smallest odd number m with a(m) > 1: a(9) = GCD(A227113(9),A227113(10)) = GCD(14,8) = 2;

a(A227289(n)) = n and a(m) <> n for m < A227289(n).

Links

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

Programs

Haskell

a227288 n = a227288_list !! (n-1)
a227288_list = zipWith gcd (tail a227113_list) a227113_list