%I A089140
%S A089140 2,4,8,15,26,40,60,84,114,149,190,234,288,346,411,484,565,649,743,840,
%T A089140 947,1063,1185
%N A089140 Number of subsequences of {1,2,3,...,n} which are p_1-sequences.
%C A089140 A p_k-sequence {x(i)} is one which is strictly monotone increasing,i.e. 
               x(i+1)>x(i) for i=1,2,3,...,n and satisfies the condition that a(k+1)=f(a(k)), 
               for k=1,2,3,...,n-1, where f is a polynomial of degree k with integer 
               coefficients.
%D A089140 John W. Layman and Bruce Landman, Note on the local growth of iterated 
               polynomials, Aeq. Math. 27 (1984), 150-156.
%e A089140 {1,2,5,14} is a p_1-subsequence of {1,2,3,...,14}, since 2=f(1), 5=f(2) 
               and 14=f(5) where f is the first degree polynomial given by f(x)=3x-1.
%Y A089140 Sequence in context: A026474 A082562 A159243 this_sequence A000125 A129961 
               A133551
%Y A089140 Adjacent sequences: A089137 A089138 A089139 this_sequence A089141 A089142 
               A089143
%K A089140 nonn
%O A089140 1,1
%A A089140 John W. Layman (layman(AT)math.vt.edu), Dec 05 2003