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A223988 Number of 3Xn 0..3 arrays with rows unimodal and columns nondecreasing 1
20, 400, 5029, 44803, 308470, 1738756, 8350154, 35158856, 132595894, 455284536, 1441678804, 4253578398, 11791889562, 30929283640, 77204065141, 184304047745, 422556706314, 933834642586, 1995549087157, 4134881948947, 8327774224280 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A223987

LINKS

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

FORMULA

Empirical: a(n) = (1/3629463552000)*n^18 + (1/44808192000)*n^17 + (10403/10461394944000)*n^16 + (10537/373621248000)*n^15 + (2915977/5230697472000)*n^14 + (6071381/747242496000)*n^13 + (748919/8211456000)*n^12 + (23111713/28740096000)*n^11 + (409218107/73156608000)*n^10 + (320706361/10450944000)*n^9 + (107018740483/804722688000)*n^8 + (467745209/1026432000)*n^7 + (10942630223/8895744000)*n^6 + (239853259979/93405312000)*n^5 + (882554800469/217945728000)*n^4 + (6093492161/1297296000)*n^3 + (4200944633/1029188160)*n^2 + (1784593/1021020)*n + 1

EXAMPLE

Some solutions for n=3

..0..2..2....0..0..3....0..1..1....1..2..0....2..1..1....0..1..0....0..1..1

..0..2..2....0..0..3....1..1..3....1..2..1....2..2..1....1..2..0....1..2..1

..3..2..2....2..3..3....3..3..3....1..2..1....3..3..2....3..2..2....1..3..2

CROSSREFS

Sequence in context: A188759 A223866 A207091 * A189698 A209433 A188988

Adjacent sequences:  A223985 A223986 A223987 * A223989 A223990 A223991

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 30 2013

STATUS

approved

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Last modified January 22 02:46 EST 2022. Contains 350481 sequences. (Running on oeis4.)