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%I #11 Oct 10 2019 13:37:30
%S 1,1,2,5,11,57,126,17609,127439468,344473534513077,
%T 891027683693605833852,
%U 156052046552117500148945259643265853536683707838813
%N a(0)=1. a(n) = the numerator of the sum of the reciprocals of the earlier terms of the sequence which are coprime to n.
%e The sequence's terms, among terms a(0) through a(5), which are coprime to 6 are a(0)=1,a(1)=1,a(3)=5 and a(4)=11. So a(6) is the numerator of 1 +1 +1/5 +1/11 = 126/55, which is 126.
%t f[l_List] := Sum[1/l[[k]], {k, Length[l]}];g[l_List] := Block[{n = Length[l]},Append[l, Numerator@f[Select[l, GCD[ #, n] == 1 &]]]];Nest[g, {1}, 12] (* _Ray Chandler_, Jan 04 2007 *)
%Y Cf. A127009.
%K nonn
%O 0,3
%A _Leroy Quet_, Jan 02 2007
%E Extended by _Ray Chandler_, Jan 04 2007
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