A223660 Number of nX2 0..3 arrays with row sums unimodal and column sums inverted unimodal

16, 256, 3060, 29922, 252912, 1912914, 13254601, 85563043, 521069404, 3022541224, 16826714534, 90449485556, 471770734372, 2397374836954, 11909366979539, 57999389713133, 277578926336176, 1308191004875392, 6081976574677816, 27936365857925926, 126946765412455656

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 31*a(n-1) -437*a(n-2) +3707*a(n-3) -21099*a(n-4) +85029*a(n-5) -249431*a(n-6) +538841*a(n-7) -856504*a(n-8) +988504*a(n-9) -804432*a(n-10) +436752*a(n-11) -141696*a(n-12) +20736*a(n-13).

Empirical g.f.: -x*( 16 -240*x +2116*x^2 -12378*x^3 +51142*x^4 -153984*x^5 +342369*x^6 -562536*x^7 +675688*x^8 -578496*x^9 +336528*x^10 -120960*x^11 +20736*x^12) / ( (-1+4*x)^2 *(x-1)^3 *(3*x-1)^4 *(2*x-1)^4 ). - R. J. Mathar, May 17 2014

Example

Some solutions for n=3:
..3..3....3..2....0..0....0..0....3..1....1..0....1..0....2..0....1..3....3..1
..1..3....2..2....1..3....0..1....0..2....2..1....3..1....0..2....2..3....0..3
..1..1....0..3....3..0....2..0....2..0....0..3....1..2....3..0....1..0....1..0

Crossrefs

Column 2 of A223663.

Sequence in context: A174335 A297377 A283860 * A223565 A223677 A207277

Adjacent sequences: A223657 A223658 A223659 * A223661 A223662 A223663

Keyword

nonn

Author

R. H. Hardin, Mar 25 2013

Status

approved