|
| |
|
|
A066319
|
|
A labeled structure simultaneously a tree and a cycle.
|
|
4
|
|
|
|
1, 1, 6, 96, 3000, 155520, 12101040, 1321205760, 192849310080, 36288000000000, 8556520581100800, 2471543044256563200, 858447696200353459200, 353034171594345598156800, 169665960401437500000000000
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,3
|
|
|
REFERENCES
|
F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, p. 68 (2.1.37).
|
|
|
LINKS
|
G. C. Greubel, Table of n, a(n) for n = 1..230
D. E. Knuth, A recurrence related to trees, Proc. Amer. Math. Soc. 105 (1989), 335-349. Reprinted as Chapter 39 of Selected Papers on Discrete Mathematics by D. E. Knuth.
Thorsten Weist, On the Euler characteristic of Kronecker moduli spaces, arXiv preprint arXiv:1203.2740 [math.RT], 2012. Cor. 5.3, k=1. But offset 0.
Index entries for sequences related to trees
|
|
|
FORMULA
|
a(n) = n^(n-2)*(n-1)!.
|
|
|
MATHEMATICA
|
Table[n!*n^(n-3), {n, 1, 20}] (* G. C. Greubel, May 29 2019 *)
|
|
|
PROG
|
(PARI) a(n) = n^(n-2)*(n-1)!; \\ Michel Marcus, May 29 2019
(Magma) [n^(n-3)*Factorial(n): n in [1..20]]; // G. C. Greubel, May 29 2019
(Sage) [n^(n-3)*factorial(n) for n in (1..20)] # G. C. Greubel, May 29 2019
|
|
|
CROSSREFS
|
Sequence in context: A304646 A251576 A126151 * A186269 A111826 A213797
Adjacent sequences: A066316 A066317 A066318 * A066320 A066321 A066322
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Christian G. Bower, Dec 13 2001
|
|
|
EXTENSIONS
|
Knuth reference from David Callan, Feb 07 2004
|
|
|
STATUS
|
approved
|
| |
|
|
