A214062 Least m>0 such that gcd(2*n+m, 2*n-1-m) > 1.

1, 3, 5, 1, 9, 11, 1, 15, 2, 1, 21, 23, 1, 2, 29, 1, 33, 35, 1, 39, 41, 1, 3, 2, 1, 51, 53, 1, 2, 3, 1, 63, 65, 1, 69, 5, 1, 75, 2, 1, 81, 83, 1, 2, 89, 1, 5, 95, 1, 99, 3, 1, 105, 2, 1, 111, 113, 1, 2, 119, 1, 6, 125, 1, 3, 131, 1, 135, 2, 1, 141, 3, 1, 2, 6, 1, 153, 155, 1

Offset

1,2

Links

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

Formula

a(n) = A214061(n)-1 for n>=1.

Example

gcd(4+1, 3-1) = gcd(4+2, 3-2) = 1 and gcd(4+3, 3-3) > 1, so that a(2) = 3.

Mathematica

b[n_] := 2 n; c[n_] := 2 n-1;
Table[m = 1; While[GCD[b[n] + m, c[n] - m] == 1, m++]; m, {n, 1, 150}]

Crossrefs

Cf. A214061.

Sequence in context: A241674 A021970 A115335 * A054586 A214229 A214728

Adjacent sequences: A214059 A214060 A214061 * A214063 A214064 A214065

Keyword

nonn,easy

Author

Clark Kimberling, Jul 25 2012

Status

approved