A127011 a(1)=1. a(n) = the numerator of the sum of the reciprocals of the earlier terms of the sequence which divide n.

1, 1, 2, 5, 11, 5, 2, 3, 7, 17, 23, 10, 2, 51, 41, 7, 35, 23, 2, 9, 55, 45, 48, 13, 12, 53, 22, 30, 2, 161, 2, 5, 80, 86, 102, 199, 2, 11, 94, 31, 83, 257, 2, 137, 46, 281, 2, 111, 16, 36, 41, 171, 107, 125, 14, 48, 7, 13, 2, 163, 2, 467, 181, 121, 179, 266, 2, 137, 167, 323, 2

Offset

1,3

Links

Table of n, a(n) for n=1..71.

Example

The sequence's terms, among terms a(1) through a(9), which divide 10 are a(1)=1, a(2)=1, a(3)=2, a(4)=5, a(6)=5 and a(7)=2. So a(10) is the numerator of 1 +1 +1/2 +1/5 +1/5 +1/2 = 17/5, which is 17.

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, Mod[n, # ] == 0 &]]]]; Nest[g, {1}, 70] (* Ray Chandler, Jan 04 2007 *)

Crossrefs

Cf. A127012.

Sequence in context: A246208 A286091 A363554 * A170868 A357588 A276736

Adjacent sequences: A127008 A127009 A127010 * A127012 A127013 A127014

Keyword

nonn

Author

Leroy Quet, Jan 02 2007

Extensions

Extended by Ray Chandler, Jan 04 2007

Status

approved