%I A036657
%S A036657 0,0,0,1,1,3,5,12,23,52,109,244,532,1196,2671,6055,13726,31380,
%T A036657 71901,165635,382610,887215,2062777,4810230,11243898,26346341,61863991,
%U A036657 145560102,343121676,810246372,1916417479,4539722153,10769366928
%N A036657 Number of n-node rooted unlabeled trees with out-degree <=2 and exactly 
               2 edges at the root.
%D A036657 S. J. Cyvin et al., Enumeration of constitutional isomers of polyenes, 
               J. Molec. Structure (Theochem), 357 (1995), 255-261.
%H A036657 <a href="Sindx_Ro.html#rooted">Index entries for sequences related to 
               rooted trees</a>
%F A036657 G.f. satisfies A(x) = (W(x)-x)*(1-x)/x-x, where W(x) is g.f. for A001190.
%p A036657 N := 40: G036657 := series(G001190*(1/x-1)-1,x,N); A036657 := n->coeff(G036657,
               x,n);
%Y A036657 First differences of A001190.
%Y A036657 Sequence in context: A161624 A034758 A131322 this_sequence A047761 A026786 
               A027246
%Y A036657 Adjacent sequences: A036654 A036655 A036656 this_sequence A036658 A036659 
               A036660
%K A036657 nonn
%O A036657 0,6
%A A036657 N. J. A. Sloane (njas(AT)research.att.com).