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%I M2989 #20 Oct 30 2017 03:34:49
%S 1,3,15,73,387,2106,11998,69999,418104,2540368,15660843,97692822,
%T 615559931,3911866377,25044058215,161369414590,1045681767924,
%U 6810222330303,44552627690401,292642818035352,1929238465836366,12760620159195044
%N E-trees with at most 3 colors.
%D G. Gati, F. Harary and R. W. Robinson, Line colored trees with extendable automorphisms, Acta Math. Scientia, 2 (1982), 105-110.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H G. Gati, F. Harary, R. W. Robinson, <a href="/A003238/a003238.pdf">Line colored trees with extendable automorphisms</a>, Acta Mathematica Scientia 2.1 (1982), 105-110. (Annotated scanned copy)
%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%F a(n) = E(3, n) where E(c, n) is defined in A007141. - _Sean A. Irvine_, Oct 29 2017
%K nonn
%O 1,2
%A _N. J. A. Sloane_.
%E More terms from _Sean A. Irvine_, Oct 29 2017
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