login
A007142
E-trees 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
OFFSET
1,2
REFERENCES
G. Gati, F. Harary and R. W. Robinson, Line colored trees with extendable automorphisms, Acta Math. Scientia, 2 (1982), 105-110.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
G. Gati, F. Harary, R. W. Robinson, Line colored trees with extendable automorphisms, Acta Mathematica Scientia 2.1 (1982), 105-110. (Annotated scanned copy)
FORMULA
a(n) = E(3, n) where E(c, n) is defined in A007141. - Sean A. Irvine, Oct 29 2017
CROSSREFS
Sequence in context: A370480 A055837 A124543 * A357222 A224397 A190010
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Sean A. Irvine, Oct 29 2017
STATUS
approved