A214071 Least m>0 such that 2^n-m and n-m are relatively prime.

1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 5, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 3, 3, 5, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 2

Offset

1,4

Links

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

Example

gcd(15,3) = 3, gcd(14,2) = 2, gcd(13,1) = 1, so that a(4) = 3.

Mathematica

b[n_] := 2^n; c[n_] := n;
Table[m = 1; While[GCD[b[n] - m, c[n] - m] != 1, m++]; m, {n, 1, 140}]
rp[n_]:=Module[{m=1, n2=2^n}, While[!CoprimeQ[n2-m, n-m], m++]; m]; Array[ rp, 100] (* Harvey P. Dale, Feb 13 2021 *)

Crossrefs

Cf. A214056.

Sequence in context: A272334 A014491 A379127 * A226915 A180173 A318668

Adjacent sequences: A214068 A214069 A214070 * A214072 A214073 A214074

Keyword

nonn,easy

Author

Clark Kimberling, Jul 26 2012

Status

approved