A223928 - OEIS

%I #6 Apr 17 2022 23:09:17

%S 22,218,1116,4498,15791,49646,142177,375777,926559,2150622,4734429,

%T 9947574,20054339,38965176,73242344,133617438,237234842,410906947,

%U 695757399,1153741182,1876668923,2998531806,4712127751,7291234403

%N Number of n X 3 0..2 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing.

%C Column 3 of A223933.

%H R. H. Hardin, <a href="/A223928/b223928.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = (1/19160064)*n^12 + (1/1064448)*n^11 + (1387/43545600)*n^10 + (577/1451520)*n^9 + (2717/414720)*n^8 + (10553/483840)*n^7 + (13338121/43545600)*n^6 + (19135/32256)*n^5 + (9514387/2177280)*n^4 + (1557389/362880)*n^3 + (1225691/118800)*n^2 + (1887533/27720)*n - 124 for n>3.

%e Some solutions for n=3

%e ..0..0..0....0..0..0....0..0..0....1..0..0....0..1..1....1..1..0....0..1..0

%e ..0..0..0....0..1..0....0..1..0....2..2..2....0..1..2....1..1..2....0..1..1

%e ..1..1..2....0..1..2....0..2..2....2..2..2....0..0..2....0..2..1....0..1..1

%Y Cf. A223933.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 29 2013