%N a(1)=1. a(n) = number of earlier terms of the sequence which divide (the number of positive integers which are <=n and missing from first (n-1) terms of sequence).
%e The positive integers which are <= 9 and are missing from the first 8 terms of the sequence are 6,7,8,9. The number of these integers is 4, so a(9) is the number of earlier terms which divide 4. Therefore a(9) = 5.
%Y Cf. A130501.
%A _Leroy Quet_, May 31 2007
%E More terms from _Sean A. Irvine_, May 26 2010