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A223951 Number of 4 X n 0..1 arrays with diagonals and antidiagonals unimodal and rows nondecreasing. 1
16, 81, 177, 321, 558, 928, 1479, 2267, 3356, 4818, 6733, 9189, 12282, 16116, 20803, 26463, 33224, 41222, 50601, 61513, 74118, 88584, 105087, 123811, 144948, 168698, 195269, 224877, 257746, 294108, 334203, 378279, 426592, 479406, 536993, 599633 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A223949.

LINKS

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

FORMULA

Empirical: a(n) = (1/3)*n^4 + (2/3)*n^3 + (37/6)*n^2 + (107/6)*n + 23 for n>2.

Conjectures from Colin Barker, Aug 24 2018: (Start)

G.f.: x*(16 + x - 68*x^2 + 86*x^3 - 7*x^4 - 33*x^5 + 13*x^6) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>7.

(End)

EXAMPLE

Some solutions for n=3:

..0..1..1....1..1..1....0..0..1....0..1..1....0..0..1....0..0..0....0..0..0

..0..0..0....0..1..1....0..0..0....1..1..1....0..0..1....1..1..1....0..1..1

..0..1..1....0..1..1....0..0..0....1..1..1....0..1..1....0..0..0....1..1..1

..0..0..1....0..1..1....0..0..1....1..1..1....0..0..1....0..0..0....0..0..1

CROSSREFS

Cf. A223949.

Sequence in context: A065771 A320965 A295071 * A041490 A096020 A016898

Adjacent sequences:  A223948 A223949 A223950 * A223952 A223953 A223954

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 29 2013

STATUS

approved

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Last modified January 19 20:22 EST 2022. Contains 350466 sequences. (Running on oeis4.)