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A069226 a(n) = gcd(n, 2^n + 1). 1
1, 1, 3, 1, 1, 1, 1, 1, 9, 5, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 27, 1, 1, 5, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 25, 3, 1, 1, 1, 11, 1, 3, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 17, 3, 5, 1, 1, 1, 1, 3, 1, 1, 13, 1, 1, 81, 1, 1, 1, 1, 1, 3, 1, 1, 5, 1, 1, 3, 1, 1, 1, 1, 1, 9, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

First occurrence of n: a(1)=1, a(3)=3, a(10)=5, a(9)=9, a(55)=11, a(78)=13, a(68)=17, a(50)=25, a(27)=27, a(406)=29, a(165)=33, a(666)=37, a(301)=43, a(1378)=53, a(1711)=59, a(390)=65, a(81)=81, a(3403)=83, a(2328)=97, a(495)=99, ... - R. J. Mathar, Dec 14 2016

LINKS

Table of n, a(n) for n=1..100.

MATHEMATICA

Table[GCD[n, 2^n+1], {n, 100}] (* Harvey P. Dale, Dec 12 2012 *)

CROSSREFS

Cf. A014491, A049095, A049096, A060444.

Sequence in context: A046535 A135939 A061653 * A016565 A051714 A023593

Adjacent sequences:  A069223 A069224 A069225 * A069227 A069228 A069229

KEYWORD

nonn

AUTHOR

Vladeta Jovovic, Apr 12 2002

STATUS

approved

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Last modified November 18 12:21 EST 2017. Contains 294891 sequences.