A127009 a(1)=1. a(n) = the numerator of the sum of the reciprocals of the earlier terms of the sequence which are coprime to n.

1, 1, 2, 2, 3, 2, 23, 164, 13389, 243985, 15948790008791, 182889846746034804193, 46520575190667784168670190084854378399767989073, 33107435283268333623593822288321538682200992783751408959931533910313916858227252552270

Offset

1,3

Links

Table of n, a(n) for n=1..14.

Example

The sequence's terms, among terms a(1) through a(7), which are coprime to 8 are a(1)=1, a(2)=1, a(5)=3 and a(7) = 23. So a(8) is the numerator of 1 +1 +1/3 +1/23 = 164/69, which is 164.

Mathematica

f[l_List] := Sum[1/l[[k]], {k, Length[l]}]; g[l_List] := Block[{n = Length[l] + 1}, Append[l, Numerator@f[Select[l, GCD[ #, n] == 1 &]]]]; Nest[g, {1}, 13] (* Ray Chandler, Jan 04 2007 *)

Crossrefs

Cf. A127010.

Sequence in context: A297935 A127012 A125503 * A181313 A334515 A164089

Adjacent sequences: A127006 A127007 A127008 * A127010 A127011 A127012

Keyword

nonn

Author

Leroy Quet, Jan 02 2007

Extensions

Extended by Ray Chandler, Jan 04 2007

Status

approved