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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A182162 Triangle read by rows: number of extensional acyclic digraphs on n labeled nodes with k sources. 4
1, 2, 12, 192, 24, 8160, 2400, 898560, 384480, 14400, 245145600, 126040320, 9777600, 50400, 159035627520, 90043269120, 9660672000, 179222400, 80640, 237882053283840, 141969202744320, 17961178152960, 547498828800, 2586608640, 802369403419852800 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

S. Wagner, Asymptotic enumeration of extensional acyclic digraphs, in Proceedings of the SIAM Meeting on Analytic Algorithmics and Combinatorics (ANALCO12); http://siam.omnibooksonline.com/2012ANALCO/data/papers/001.pdf

LINKS

Table of n, a(n) for n=1..25.

EXAMPLE

Triangle begins:

1

2

12

192 24

8160 2400

898560 384480 14400

245145600 126040320 9777600 50400

...

MAPLE

A001192 := proc(n) option remember: if(n=0)then return 1: fi: return add((-1)^(n-k-1)*binomial(2^k-k, n-k)*procname(k), k=0..n-1); end: A182162 := proc(n, l) local vl: vl := add((-1)^(k-l)*binomial(n, k)*binomial(k, l)*binomial(2^(n-k)-n+k, k)*k!*(n-k)!*A001192(n-k), k=l..n): if(vl = 0)then return NULL: fi: return vl: end: for n from 1 to 10 do seq(A182162(n, l), l=1..n); od; # Nathaniel Johnston, Apr 18 2012

CROSSREFS

Row sums give A182161. First column is A182163. Row lengths are A182220.

Sequence in context: A007764 A015195 A051421 * A258994 A110105 A182163

Adjacent sequences:  A182159 A182160 A182161 * A182163 A182164 A182165

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane, Apr 15 2012

EXTENSIONS

a(15) - a(25) from Nathaniel Johnston, Apr 18 2012

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 December 11 07:47 EST 2019. Contains 329914 sequences. (Running on oeis4.)