A127012 a(0)=1. a(n) = the numerator of the sum of the reciprocals of the earlier terms of the sequence which divide n.

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, 2, 15, 2, 129, 7, 15, 96, 307, 2, 8, 94, 69, 2, 68, 2, 19, 37, 208, 95, 163, 19, 9, 7, 249, 107, 173, 111, 587, 139, 9, 2, 319, 2, 10, 215, 171, 27, 21, 2, 749, 55, 402, 2, 99, 2, 853, 37

Offset

0,3

Links

Table of n, a(n) for n=0..75.

Example

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.

Mathematica

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 *)

Crossrefs

Cf. A127011.

Sequence in context: A329350 A283450 A297935 * A125503 A127009 A181313

Adjacent sequences: A127009 A127010 A127011 * A127013 A127014 A127015

Keyword

nonn

Author

Leroy Quet, Jan 02 2007

Extensions

Extended by Ray Chandler, Jan 04 2007

Status

approved