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%I #13 Oct 11 2019 12:33:02
%S 1,1,1,2,3,1,1,2,3,5,1,6,7,1,1,2,3,5,1,6,7,13,5,18,23,41,1,14,15,1,1,
%T 2,3,5,1,6,7,13,5,2,7,9,1,10,1,11,3,14,17,31,3,2,5,7,1,8,9,17,13,30,
%U 43,73,29,34,63,97,5,102,107,209,79,288,367,655,511,1166,1677,2843,565,3408
%N a(0) = a(1) = 1. For n >= 2, a(n) = largest divisor of (a(n-1) + a(n-2)) which is coprime to n.
%H G. C. Greubel, <a href="/A123338/b123338.txt">Table of n, a(n) for n = 0..1000</a>
%e a(20)+a(21) = 20. The largest divisor of 20 which is coprime to 22 is 5. So a(22) = 5.
%t t[n_, m_] := Last[Select[Divisors[m], GCD[ #, n] == 1 &]];f[l_List] := Append[l, t[Length[l], l[[ -1]] + l[[ -2]]]];Nest[f, {1, 1}, 80] (* _Ray Chandler_, Oct 17 2006 *)
%K nonn
%O 0,4
%A _Leroy Quet_, Oct 11 2006
%E Extended by _Ray Chandler_, Oct 17 2006