%I #6 Mar 30 2012 18:58:07
%S 0,0,1,2,7,36,391,17536,7520303,134830884224,1016333764230127711,
%T 137040823237740906153712364032,
%U 139279234211744145176797121311869355242595356863
%N a(n)=f(a(n-1)+1,a(n-2),a(n-3)+1), where f(x,y,z)=yz+zx+xy and (a(1),a(2),a(3))=(0,0,1).
%C For a guide to related sequences, see A203761.
%t a[1] = 0; a[2] = 0; a[3] = 1;
%t a[n_] := SymmetricPolynomial[2, {1 + a[n - 1], a[n - 2], 1 + a[n - 3]}]
%t Table[a[n], {n, 1, 16}] (* A203900 *)
%Y Cf. A203761.
%K nonn
%O 1,4
%A _Clark Kimberling_, Jan 07 2012