%I #12 Oct 26 2019 09:58:52
%S 1,2,4,10,34,146,752,4520,31062,240188,2063846,19508770,201184666,
%T 2247704104,27044622168,348654862510,4794539357488,70054014476102,
%U 1083796147054274,17698938549553490,304247125951777284
%N Related to label-increasing forests with branching bounded by 3.
%C Sequence B_n(2) in Riordan 1978 or 1979.
%H John Riordan, <a href="/A297196/a297196.pdf">Forests of label-increasing trees</a>, annotated scanned copy of 1978 pre-publication version.
%H John Riordan, <a href="https://doi.org/10.1002/jgt.3190030204">Forests of label-increasing trees</a>, J. Graph Theory, 3 (1979), 127-133.
%F E.g.f.: F(x)^2, where F(x) is the e.g.f. for A297196. - _Max Alekseyev_, Jul 12 2019
%Y Cf. A297196, A297198, A297200, A297201, A297202, A297203, A297204.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Jan 10 2018
%E Edited and extended by _Max Alekseyev_, Jul 12 2019