A214180 Least m>0 such that 2^n-m and 5^n-m are relatively prime.

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

Offset

1,2

Comments

a(616) = 5.

Links

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

Example

gcd(16-1,625-1) = 3, gcd(16-2,625-2) = 7, gcd(16-3,625-3) = 1, so a(4) = 3.

Mathematica

Table[m = 1; While[GCD[2^n - m, 5^n - m] != 1, m++]; m, {n, 1, 140}]

Crossrefs

Cf. A214074, A214708.

Sequence in context: A349258 A349326 A185894 * A343073 A184166 A029423

Adjacent sequences: A214177 A214178 A214179 * A214181 A214182 A214183

Keyword

nonn,easy

Author

Clark Kimberling, Jul 27 2012

Status

approved