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A129088 a(1)=a(2)=1. a(n) = GCD(a(n-1),n) + GCD(a(n-2),n). 1

%I

%S 1,1,2,3,2,5,2,3,4,3,2,5,2,3,4,5,2,3,2,3,4,3,2,5,6,3,6,3,2,5,2,3,4,3,

%T 2,5,2,3,4,5,2,3,2,3,4,3,2,5,2,7,2,3,2,5,6,3,6,3,2,5,2,3,4,5,6,7,2,3,

%U 4,3,2,5,2,3,4,5,2,3,2,3,4,3,2,5,6,3,6,3,2,5,2,3,4,3,2,5,2,3,4,5,2,3,2,3,4

%N a(1)=a(2)=1. a(n) = GCD(a(n-1),n) + GCD(a(n-2),n).

%C a(2n) is odd for all n >=1. a(2n-1) is even for all n >=2.

%p a[1]:=1: a[2]:=1: for n from 3 to 140 do a[n]:=gcd(a[n-1],n)+gcd(a[n-2],n) od: seq(a[n],n=1..140); - _Emeric Deutsch_, Apr 04 2007

%Y Cf. A129089.

%K nonn

%O 1,3

%A _Leroy Quet_, Mar 29 2007

%E More terms from _Emeric Deutsch_, Apr 04 2007

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Last modified January 23 03:08 EST 2019. Contains 319370 sequences. (Running on oeis4.)