

A007152


Evolutionary trees of magnitude n.
(Formerly M3628)


2



1, 1, 4, 28, 301, 4466, 84974, 1974904, 54233540, 1718280152, 61695193880, 2475688513024, 109797950475448, 5333253012414224, 281576039542538368, 16055279332196218624, 983264280857581866112, 64369946360185677026048, 4485859513184032011682304, 331558482325457407154881024
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OFFSET

1,3


REFERENCES

L. R. Foulds and R. W. Robinson, Counting certain classes of evolutionary trees with singleton labels, Congress. Num., 44 (1984), 6588.
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..20.
L. R. Foulds and R. W. Robinson, Counting certain classes of evolutionary trees with singleton labels, Congress. Num., 44 (1984), 6588. (Annotated scanned copy)
Index entries for sequences related to trees


MAPLE

Q := proc(n)
option remember ;
if n <= 1 then
0;
else
A007151(n)A007151(n1) +(n1)*procname(n1) ; # eq (3.5)
%/2 ;
end if;
end proc:
A007152 := proc(n)
if n = 1 then
1;
else
A007151(n1)+Q(n1) ; # eq (3.9)
end if ;
end proc:
seq(A007152(n), n=1..20 ); # R. J. Mathar, Mar 19 2018


CROSSREFS

Cf. A007151.
Sequence in context: A112938 A307083 A274043 * A295258 A177554 A316212
Adjacent sequences: A007149 A007150 A007151 * A007153 A007154 A007155


KEYWORD

nonn,easy


AUTHOR

Robert W. Robinson


STATUS

approved



