This site is supported by donations to The OEIS Foundation.



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

(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A105344 Number of ways of placing n balls into n boxes and then into n containers. 0
1, 4, 12, 45 (list; graph; refs; listen; history; text; internal format)



Table of n, a(n) for n=1..4.


a(2): We can have either 2 balls in a box and the other box empty, or a ball in each box. We may place both the boxes into one container, or one in each.

So we have [(2)()][], [(1)(1)][], [(2)][()] and [(1)][(1)], hence a(2)=4.

For a(3) we have: (0 is an empty box, / is a new container, - is an empty container)

300/-/-, 30/0/-, 3/00/-, 3/0/0

210/-/-, 21/0/-, 20/1/-, 2/10/-, 2/1/0

111/-/-, 11/1/-, 1/1/1

total 12


Cf. A000041.

Sequence in context: A065143 A098543 A028407 * A074035 A149366 A149367

Adjacent sequences:  A105341 A105342 A105343 * A105345 A105346 A105347




Jon Perry, Apr 30 2005



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 16 04:05 EST 2019. Contains 330013 sequences. (Running on oeis4.)