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A227260 Number of nX3 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X4 binary array having a sum of two or less, with rows and columns of the latter in lexicographically nondecreasing order 1
4, 23, 98, 353, 1111, 3136, 8065, 19146, 42385, 88282, 174361, 328741, 595043, 1038979, 1757024, 2887631, 4625512, 7239575, 11095178, 16681436, 24644396, 35826978, 51316667, 72502032, 101139243, 139429856, 190111239, 256561119 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A227263

LINKS

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

FORMULA

Empirical: a(n) = (1/90720)*n^9 + (11/40320)*n^8 + (53/30240)*n^7 + (73/2880)*n^6 + (301/4320)*n^5 - (2683/5760)*n^4 + (448811/90720)*n^3 + (1613/1120)*n^2 - (83207/2520)*n + 33 for n>5

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A014585 A305588 A317006 * A316871 A197854 A317599

Adjacent sequences:  A227257 A227258 A227259 * A227261 A227262 A227263

KEYWORD

nonn

AUTHOR

R. H. Hardin Jul 04 2013

STATUS

approved

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Last modified July 24 02:05 EDT 2021. Contains 346269 sequences. (Running on oeis4.)