A127012 - OEIS

%I #10 Oct 10 2019 11:52:46

%S 1,1,2,2,3,2,23,2,4,7,4,2,16,2,36,7,89,2,35,2,13,55,6,47,7,2,171,7,53,

%T 2,15,2,129,7,15,96,307,2,8,94,69,2,68,2,19,37,208,95,163,19,9,7,249,

%U 107,173,111,587,139,9,2,319,2,10,215,171,27,21,2,749,55,402,2,99,2,853,37

%N a(0)=1. a(n) = the numerator of the sum of the reciprocals of the earlier terms of the sequence which divide n.

%e The sequence's terms, among terms a(0) through a(8), which divide 9 are a(0)=1, a(1)=1 and a(4)=3. So a(9) is the numerator of 1 +1 +1/3 = 7/3, which is 7.

%t f[l_List] := Sum[1/l[[k]], {k, Length[l]}];g[l_List] := Block[{n = Length[l]},Append[l, Numerator@f[Select[l, Mod[n, # ] == 0 &]]]];Nest[g, {1}, 75] (* _Ray Chandler_, Jan 04 2007 *)

%Y Cf. A127011.

%K nonn

%O 0,3

%A _Leroy Quet_, Jan 02 2007

%E Extended by _Ray Chandler_, Jan 04 2007