A214721 Least m>0 such that 2*n+1+m and n-m are not relatively prime.

1, 2, 1, 4, 1, 6, 1, 3, 1, 10, 1, 12, 1, 14, 1, 2, 1, 3, 1, 20, 1, 22, 1, 24, 1, 26, 1, 3, 1, 2, 1, 32, 1, 34, 1, 36, 1, 3, 1, 7, 1, 42, 1, 2, 1, 46, 1, 3, 1, 50, 1, 52, 1, 54, 1, 4, 1, 2, 1, 60, 1, 7, 1, 64, 1, 66, 1, 3, 1, 70, 1, 2, 1, 74, 1, 76, 1, 3, 1, 80, 1

Offset

1,2

Links

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

Example

gcd(17,7) = 1, gcd(19,6) = 1, gcd(20,5) = 5, so a(8) = 3.

Mathematica

Table[m = 1; While[GCD[2n+1+m, n - m] != 1, m++]; m, {n, 1, 140}]

Crossrefs

Cf. A214060.

Sequence in context: A076512 A128707 A257022 * A324384 A340081 A346467

Adjacent sequences: A214718 A214719 A214720 * A214722 A214723 A214724

Keyword

nonn,easy

Author

Clark Kimberling, Jul 28 2012

Status

approved