A214715 Least m>0 such that prime(n+1)-m and n-m are relatively prime.

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

Offset

1,1

Links

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

Example

gcd(89-1,11-1) = 2, gcd(89-2,11-2) = 3, gcd(89-3,11-3) = 2, gcd(89-4,11-4) = 1, so a(23) = 4.

Mathematica

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

Crossrefs

Cf. A214714.

Sequence in context: A064547 A318306 A345935 * A244145 A371734 A086435

Adjacent sequences: A214712 A214713 A214714 * A214716 A214717 A214718

Keyword

nonn,easy

Author

Clark Kimberling, Jul 27 2012

Status

approved