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!)
A058407 Number of 3 X n nonnegative integer matrices with all column sums 3, up to row and column permutation. 6
1, 3, 13, 44, 134, 356, 876, 1966, 4146, 8236, 15592, 28252, 49357, 83377, 136837, 218728, 341554, 522064, 782810, 1153180, 1671698, 2387568, 3363738, 4679208, 6433183, 8748119, 11775343, 15699188, 20744108, 27180308, 35332850, 45588746 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of 3 X n nonnegative integer matrices with all column sums equal to m, up to row and column permutation, is coefficient of x^n in expansion of 1 / 6 * (1 / (1 - x)^C(m + 2,2) + 3 / (1 - x)^floor((m + 2) / 2) / (1 - x^2)^(C(m + 2,2) - floor((m + 2) / 2)) / 2 + 2 / (1 - x)^(C(m + 2,2) - 3 * floor(C(m + 2,2) / 3)) / (1 - x^3)^floor(C(m + 2,2) / 3)).

LINKS

Table of n, a(n) for n=0..31.

Number of m x l nonnegative integer matrices with all column sums equal to n, up to row and column permutation

FORMULA

G.f.: 1/6*(1/(1-x)^10+3/(1-x)^2/(1-x^2)^4+2/(1-x)/(1-x^3)^3).

CROSSREFS

Cf. A050531, A058389, A058408.

Sequence in context: A284194 A209296 A193041 * A095863 A136520 A212416

Adjacent sequences:  A058404 A058405 A058406 * A058408 A058409 A058410

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, Nov 25 2000

EXTENSIONS

More terms from Max Alekseyev, Jun 21 2011

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 13 03:41 EST 2019. Contains 329968 sequences. (Running on oeis4.)