A214060 Least m>0 such that gcd(2*n-1+m, n-m) > 1.

1, 2, 1, 4, 1, 6, 1, 8, 1, 10, 1, 2, 1, 14, 1, 16, 1, 18, 1, 20, 1, 2, 1, 24, 1, 4, 1, 28, 1, 30, 1, 2, 1, 34, 1, 36, 1, 38, 1, 5, 1, 2, 1, 44, 1, 46, 1, 4, 1, 50, 1, 2, 1, 5, 1, 56, 1, 58, 1, 60, 1, 2, 1, 64, 1, 66, 1, 5, 1, 4, 1, 2, 1, 6, 1, 76, 1, 78, 1, 80, 1, 2, 1, 84, 1, 86, 1

Offset

1,2

Links

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

Example

gcd(23+1,12-1) = 1 and gcd(23+2,12-2) > 1, so that a(12) = 2.

Mathematica

b[n_] := 2*n - 1; c[n_] := n;
Table[m = 1; While[GCD[b[n] + m, c[n] - m] == 1, m++]; m, {n, 1, 150}]
lmg[n_]:=Module[{m=1}, While[GCD[2n-1+m, n-m]<2, m++]; m]; Array[lmg, 90] (* Harvey P. Dale, Jan 14 2020 *)

Crossrefs

Cf. A214057, A214061, A214062.

Sequence in context: A083258 A083259 A342242 * A009531 A124625 A327512

Adjacent sequences: A214057 A214058 A214059 * A214061 A214062 A214063

Keyword

nonn,easy

Author

Clark Kimberling, Jul 24 2012

Status

approved