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%I #5 Mar 31 2012 13:21:32
%S 1,1,2,5,17,66,307,1619,9668,64112,469936,3773496,32997159,312542002,
%T 3192352420,35023164817,411288004670,5154265796088,68746349160704,
%U 973526723323087,14605620692012861,231694886107899371
%N Number of sequences b with last index n with b(0) = 1, b(i+1) = b(i)+d where d|b(i).
%C b(n) can be as large as 2^n. [From _Max Alekseyev_, May 10 2009]
%e For n=3, the sequences are 1,2,3,4; 1,2,3,6; 1,2,4,5; 1,2,4,6; and 1,2,4,8. We can't have 1,2,3,5 because the difference (5-3) does not divide 3.
%Y Cf. A117497, A122205.
%K nonn
%O 0,3
%A _Franklin T. Adams-Watters_, Aug 25 2006
%E a(15)..a(21) from _Max Alekseyev_, May 10 2009