A214714 Least m>0 such that prime(n)-m and n-m are relatively prime.

1, 1, 2, 2, 4, 1, 4, 1, 4, 1, 2, 1, 2, 1, 2, 1, 4, 1, 2, 1, 2, 2, 4, 1, 2, 3, 2, 1, 2, 1, 2, 1, 2, 2, 4, 2, 6, 1, 2, 1, 4, 1, 2, 1, 2, 2, 2, 1, 2, 1, 4, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 4, 1, 2, 1, 2, 1, 2, 2, 4, 1, 2, 1, 2, 1, 4, 2, 4, 1, 2, 2, 4, 1, 2, 3, 2

Offset

1,3

Comments

Does every positive integer occur?

Links

Clark Kimberling, Table of n, a(n) for n = 1..1000

Example

gcd(16,6) = 2, gcd(15,5) = 5, gcd(14,4) = 2, gcd(13,3) = 1, so a(7) = 4.

Mathematica

Table[m = 1; While[GCD[Prime[n] - m, n - m] != 1, m++]; m, {n, 1, 140}]

Crossrefs

Cf. A214052.

Sequence in context: A264799 A248503 A359855 * A023137 A327488 A065273

Adjacent sequences: A214711 A214712 A214713 * A214715 A214716 A214717

Keyword

nonn,easy

Author

Clark Kimberling, Jul 27 2012

Status

approved