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A223670 Number of 3 X n 0..1 arrays with rows, diagonals and antidiagonals unimodal. 2
8, 64, 292, 948, 2527, 5913, 12577, 24821, 46068, 81198, 136930, 222250, 348885, 531823, 789879, 1146307, 1629458, 2273484, 3119088, 4214320, 5615419, 7387701, 9606493, 12358113, 15740896, 19866266, 24859854, 30862662, 38032273, 46544107 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A223669.

LINKS

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

FORMULA

Empirical: a(n) = (23/360)*n^6 - (3/40)*n^5 + (37/18)*n^4 + (119/24)*n^3 - (3103/360)*n^2 + (997/60)*n - 9 for n>1.

Conjectures from Colin Barker, Mar 16 2018: (Start)

G.f.: x*(8 + 8*x + 12*x^2 - 32*x^3 + 63*x^4 - 16*x^5 + 5*x^6 - 2*x^7) / (1 - x)^7.

a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>8.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

CROSSREFS

Cf. A223669.

Sequence in context: A167239 A236554 A173502 * A189618 A189690 A188741

Adjacent sequences:  A223667 A223668 A223669 * A223671 A223672 A223673

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 25 2013

STATUS

approved

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Last modified May 19 05:04 EDT 2022. Contains 353826 sequences. (Running on oeis4.)