|
Search: id:A143360
|
|
|
| A143360 |
|
Sum of root degrees of all symmetric ordered trees with n edges. |
|
+0
2
|
|
| 1, 3, 5, 12, 20, 45, 77, 168, 294, 630, 1122, 2376, 4290, 9009, 16445, 34320, 63206, 131274, 243542, 503880, 940576, 1939938, 3640210, 7488432, 14115100, 28973100, 54826020, 112326480, 213286590, 436268025, 830905245, 1697168160, 3241119750
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
a(n)=Sum(A143359(n,k),k=1..n).
|
|
FORMULA
|
G.f.=z*[C(z^2)]^2*[1+2z*C(z^2)]/[1-z*C(z^2)], where C(z)=[1-sqrt(1-4z)]/(2z) is the g.f. of the Catalan numbers (A000108).
|
|
MAPLE
|
C:=proc(z) options operator, arrow: (1/2-(1/2)*sqrt(1-4*z))/z end proc: G:=z*C(z^2)^2*(1+2*z*C(z^2))/(1-z*C(z^2)): Gser:=series(G, z=0, 40): seq(coeff(Gser, z, n), n=1..34);
|
|
CROSSREFS
|
Cf. A000108, A143359.
Sequence in context: A024458 A143643 A089292 this_sequence A034763 A121482 A013498
Adjacent sequences: A143357 A143358 A143359 this_sequence A143361 A143362 A143363
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 15 2008
|
|
|
Search completed in 0.002 seconds
|
