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A214056 Least m>0 such that 2^n+m and n-m have a common divisor > 1. 4
1, 2, 3, 2, 5, 1, 1, 2, 9, 2, 11, 2, 1, 2, 15, 2, 3, 2, 1, 2, 8, 2, 23, 2, 1, 1, 2, 2, 29, 2, 1, 2, 3, 2, 35, 2, 1, 2, 39, 2, 41, 2, 1, 2, 1, 1, 2, 2, 1, 2, 14, 1, 2, 2, 1, 2, 57, 2, 3, 2, 1, 2, 63, 2, 65, 1, 1, 2, 6, 2, 6, 2, 1, 2, 75, 2, 77, 2, 1, 2, 81, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

EXAMPLE

gcd(2^4+1,4-1) = 1 and gcd(2^4+2,4-2) = 2, so a(4) = 2.

MATHEMATICA

b[n_] := 2^n; c[n_] := n;

Table[m = 1; While[GCD[b[n] + m, c[n] - m] == 1, m++]; m, {n, 1, 100}]

CROSSREFS

Cf. A214057.

Sequence in context: A120007 A092509 A214053 * A014973 A276835 A157753

Adjacent sequences:  A214053 A214054 A214055 * A214057 A214058 A214059

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Jul 22 2012

STATUS

approved

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Last modified May 18 19:58 EDT 2021. Contains 344002 sequences. (Running on oeis4.)