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A223660 Number of nX2 0..3 arrays with row sums unimodal and column sums inverted unimodal 2
16, 256, 3060, 29922, 252912, 1912914, 13254601, 85563043, 521069404, 3022541224, 16826714534, 90449485556, 471770734372, 2397374836954, 11909366979539, 57999389713133, 277578926336176, 1308191004875392, 6081976574677816 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A223663

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

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

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Last modified October 21 15:18 EDT 2021. Contains 348155 sequences. (Running on oeis4.)