OFFSET
1,3
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(11)*a(12) = 6*8 = 48. The terms, from among the first 12 terms of the sequence, which divide 48 are: a(1)=1, a(2)=1, a(3)=2, a(4)=3, a(5)=4, a(8)=4, a(10)=6, a(11)=6 and a(12)=8. There are 9 such terms, so a(13) = 9.
MAPLE
a[1]:=1: a[2]:=1: for n from 3 to 70 do a[n]:=0: for i to n-1 do if type(a[n-1]*a[n-2]/a[i], integer)=true then a[n]:=a[n]+1 else end if end do end do: seq(a[n], n=1..70); # Emeric Deutsch, Oct 16 2007
MATHEMATICA
a = {1, 1}; Do[AppendTo[a, Length[Select[Range[Length[a]], Mod[a[[ -1]]*a[[ -2]], a[[ # ]]] == 0 &]]], {80}]; a (* Stefan Steinerberger, Oct 07 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Oct 04 2007
EXTENSIONS
More terms from Stefan Steinerberger, Oct 07 2007
STATUS
approved