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A127203 a(n) = gcd(A127202(n), A127202(n+1)). 3

%I

%S 1,2,1,3,1,5,1,7,2,1,3,1,11,1,13,1,3,2,1,17,1,19,2,1,3,1,23,1,5,3,1,4,

%T 1,29,1,31,1,3,1,5,1,37,1,3,1,41,1,43,2,1,3,1,47,1,7,2,1,3,2,1,53,1,5,

%U 3,1,59,1,61,1,3,2,1,5,1,67,2,1,3,1,71,1,73,1,3,2,1,7,1,79,2,1,3,1,83,1,5,2

%N a(n) = gcd(A127202(n), A127202(n+1)).

%C a(n) never equals a(n+1), by decree.

%C For the first 719 terms this coincides with the sequence {gcd(A280985(n), A280985(n+1)}. By decree, the latter may not contain two consecutive 1's. - _N. J. A. Sloane_, Jan 21 2017

%H Rémy Sigrist, <a href="/A127203/b127203.txt">Table of n, a(n) for n = 1..10000</a>

%t f[l_List] := Block[{k = 1, c = GCD[l[[ -1]], l[[ -2]]]},While[MemberQ[l, k] || GCD[k, l[[ -1]]] == c, k++ ];Append[l, k]]; GCD @@@ Partition[Nest[f, {1, 2}, 100], 2, 1] (* _Ray Chandler_, Jan 16 2007 *)

%Y Cf. A127202, A280985.

%K nonn

%O 1,2

%A _Leroy Quet_, Jan 08 2007

%E Extended by _Ray Chandler_, Jan 16 2007

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Last modified April 7 04:20 EDT 2020. Contains 333292 sequences. (Running on oeis4.)