login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A059523 Number of n-element unlabeled ordered T_0-antichains without isolated vertices; number of T_1-hypergraphs (without empty edge and without multiple edges) on n labeled vertices. 16
1, 2, 2, 36, 19020, 2010231696, 9219217412568364176, 170141181796805105960861096082778425120, 57896044618658097536026644159052312977171804852352892309392604715987334365792 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

G. Kilibarda and V. Jovovic, "Enumeration of some classes of T_0-hypergraphs", in preparation, 2004.

LINKS

Table of n, a(n) for n=0..8.

V. Jovovic, T_1-hyper graphs on a labeled 3-set

Goran Kilibarda and Vladeta Jovovic, Antichains of Multisets, J. Integer Seqs., Vol. 7, 2004.

FORMULA

a(n)=A059052(n)/2.

EXAMPLE

Number of k-element T_1-hipergraphs (without empty edge and without multiple edges) on 3 labeled vertices is

C(7,k)-6*C(5,k)+6*C(4,k)+3*C(3,k)-6*C(2,k)+2*C(1,k),k=0..7; so a(3)=2+11+15+7+1=36=2^7-6*2^5+6*2^4+3*2^3-6*2^2+2*2.

CROSSREFS

Cf. A003465, A059201, A059052, A326961.

Sequence in context: A131657 A298993 A267345 * A038623 A001121 A202711

Adjacent sequences:  A059520 A059521 A059522 * A059524 A059525 A059526

KEYWORD

nonn

AUTHOR

Vladeta Jovovic and Goran Kilibarda, Jan 20 2001; revised Jun 03 2004

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 19 16:17 EDT 2019. Contains 328223 sequences. (Running on oeis4.)