

A007142


Etrees with at most 3 colors.
(Formerly M2989)


1



1, 3, 15, 73, 387, 2106, 11998, 69999, 418104, 2540368, 15660843, 97692822, 615559931, 3911866377, 25044058215, 161369414590, 1045681767924, 6810222330303, 44552627690401, 292642818035352, 1929238465836366, 12760620159195044
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


REFERENCES

G. Gati, F. Harary and R. W. Robinson, Line colored trees with extendable automorphisms, Acta Math. Scientia, 2 (1982), 105110.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=1..22.
G. Gati, F. Harary, R. W. Robinson, Line colored trees with extendable automorphisms, Acta Mathematica Scientia 2.1 (1982), 105110. (Annotated scanned copy)
Index entries for sequences related to trees


FORMULA

a(n) = E(3, n) where E(c, n) is defined in A007141.  Sean A. Irvine, Oct 29 2017


CROSSREFS

Sequence in context: A232289 A055837 A124543 * A224397 A190010 A151326
Adjacent sequences: A007139 A007140 A007141 * A007143 A007144 A007145


KEYWORD

nonn


AUTHOR

N. J. A. Sloane.


EXTENSIONS

More terms from Sean A. Irvine, Oct 29 2017


STATUS

approved



