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A223766
Number of n X 4 0..1 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing
1
11, 56, 155, 361, 782, 1601, 3141, 5907, 10678, 18618, 31422, 51505, 82243, 128276, 195884, 293448, 432009, 625939, 893739, 1258980, 1751404, 2408203, 3275495, 4410017, 5881056, 7772640, 10186012, 13242411, 17086185, 21888262, 27850006
OFFSET
1,1
COMMENTS
Column 4 of A223770.
LINKS
FORMULA
Empirical: a(n) = (1/40320)*n^8 - (1/10080)*n^7 + (3/320)*n^6 + (1/45)*n^5 + (1109/1920)*n^4 - (4837/1440)*n^3 + (422483/10080)*n^2 - (109337/840)*n + 226 for n>4.
Conjectures from Colin Barker, Aug 22 2018: (Start)
G.f.: x*(11 - 43*x + 47*x^2 + 58*x^3 - 205*x^4 + 209*x^5 - 42*x^6 - 150*x^7 + 256*x^8 - 245*x^9 + 151*x^10 - 55*x^11 + 9*x^12) / (1 - x)^9.
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>13.
(End)
EXAMPLE
Some solutions for n=3:
..1..1..1..0....0..0..1..1....0..0..1..0....1..0..0..0....0..1..1..0
..0..1..1..1....0..1..1..1....1..1..1..1....0..1..0..0....0..1..1..1
..0..1..1..1....1..1..1..1....1..1..1..1....0..0..1..1....0..0..1..1
CROSSREFS
Cf. A223770.
Sequence in context: A099532 A041226 A042503 * A265151 A275643 A341405
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 27 2013
STATUS
approved