A256366 Primes arising in A=A256189 as gcd(A(n-2), A(n)), n > 3.

2, 3, 2, 3, 5, 3, 5, 2, 5, 2, 3, 7, 3, 7, 2, 5, 11, 5, 11, 2, 3, 13, 17, 13, 17, 3, 2, 19, 2, 19, 2, 5, 2, 5, 2, 5, 2, 5, 23, 3, 23, 2, 23, 29, 3, 29, 2, 7, 2, 7, 2, 3, 2, 3, 31, 3, 31, 2, 31, 2, 3, 2, 11, 2

Offset: 2

Author

Vladimir Shevelev, Mar 26 2015

Keywords

• nonn

Comments

Conjecture: the sequence contains all primes such that the first appearances of them are in the natural order.

Provided all primes appear, they must appear in the natural order. Suppose otherwise: For A=A256189 and some n and primes p < q, q divides a = A(n) but not A(k) for k < n and p does not divide A(k) for k <= n. But then A(n) should be pa/q. - Danny Rorabaugh, Mar 31 2015

Links

• Peter J. C. Moses, Table of n, a(n) for n = 2..1001

Crossrefs

Cf. A256189.