A266931 - OEIS

A266931

Number of n X 4 binary arrays with rows lexicographically nondecreasing and columns lexicographically nondecreasing and row sums nondecreasing and column sums nonincreasing.

2, 5, 12, 35, 100, 288, 794, 2077, 5110, 11869, 26086, 54543, 108999, 209148, 386883, 692473, 1203061, 2034487, 3357115, 5416951, 8563297, 13284702, 20254831, 30390893, 44926915, 65505045, 94288435, 134099783, 188589873, 262441858

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OFFSET

1,1

COMMENTS

Column 4 of A266935.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..64

FORMULA

Empirical: a(n) = 2*a(n-1) +3*a(n-2) -4*a(n-3) -9*a(n-4) -a(n-5) +19*a(n-6) +13*a(n-7) -13*a(n-8) -25*a(n-9) -11*a(n-10) +15*a(n-11) +22*a(n-12) +17*a(n-13) -4*a(n-14) -23*a(n-15) -23*a(n-16) -4*a(n-17) +17*a(n-18) +22*a(n-19) +15*a(n-20) -11*a(n-21) -25*a(n-22) -13*a(n-23) +13*a(n-24) +19*a(n-25) -a(n-26) -9*a(n-27) -4*a(n-28) +3*a(n-29) +2*a(n-30) -a(n-31).

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Cf. A266935.

Sequence in context: A350441 A181899 A131267 * A148286 A075202 A075203

Adjacent sequences: A266928 A266929 A266930 * A266932 A266933 A266934

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 06 2016

STATUS

approved