A070307 Number of n X n matrices with nonnegative integer entries such that every row sum equals 3.

1, 16, 1000, 160000, 52521875, 30840979456, 29509034655744, 42998169600000000, 90647430472564453125, 265599227914240000000000, 1047192117300356121695451136, 5410240907043328777415185924096, 35821862005173382840059779052734375, 298285661929377847941529600000000000000

Offset

1,2

Links

Indranil Ghosh, Table of n, a(n) for n = 1..160

Formula

a(n) = C(n+2, 3)^n = A000292(n)^n.

Mathematica

Table[ Binomial[n + 2, 3]^n, {n, 1, 14}]

Prog

(PARI) a(n) = binomial(n+2, 3)^n; \\ Michel Marcus, Mar 10 2017
(Python)
import math
f=math.factorial
def C(n, r): return f(n)/ f(r)/ f(n-r)
def A070307(n): return C(n + 2, 3)**n # Indranil Ghosh, Mar 10 2017

Crossrefs

Cf. A061718, A000292.

Sequence in context: A024301 A211090 A160012 * A159683 A197104 A358051

Adjacent sequences: A070304 A070305 A070306 * A070308 A070309 A070310

Keyword

nonn

Author

Sharon Sela (sharonsela(AT)hotmail.com), May 10 2002

Extensions

More terms from Robert G. Wilson v, May 10 2002

More terms from Michel Marcus, Mar 10 2017

Status

approved