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

1,2

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

Prog

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

Crossrefs

Sequence in context: A130008 A101809 A127203 * A336752 A126132 A129982

Adjacent sequences: A227285 A227286 A227287 * A227289 A227290 A227291

Keyword

nonn

Author

Reinhard Zumkeller, Jul 05 2013

Status

approved