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A227103 T(n,k)=Number of nXk 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X(k+1) binary array having a sum of two, with rows and columns of the latter in lexicographically nondecreasing order 6
2, 4, 4, 7, 15, 7, 11, 48, 48, 11, 16, 136, 239, 136, 16, 22, 341, 1084, 1084, 341, 22, 29, 771, 4444, 8427, 4444, 771, 29, 37, 1606, 16366, 60039, 60039, 16366, 1606, 37, 46, 3133, 54500, 384591, 754758, 384591, 54500, 3133, 46, 56, 5789, 166271, 2209056 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Table starts

..2....4......7.......11........16.........22.........29..........37.........46

..4...15.....48......136.......341........771.......1606........3133.......5789

..7...48....239.....1084......4444......16366......54500......166271.....470106

.11..136...1084.....8427.....60039.....384591....2209056....11456481...54141062

.16..341...4444....60039....754758....8638999...89104481...828893716.6983821643

.22..771..16366...384591...8638999..180409504.3428152304.58981679762

.29.1606..54500..2209056..89104481.3428152304

.37.3133.166271.11456481.828893716

.46.5789.470106.54141062

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..84

FORMULA

Empirical for column k:

k=1: a(n) = (1/2)*n^2 + (1/2)*n + 1

k=2: [polynomial of degree 7] for n>3

k=3: [polynomial of degree 15] for n>5

k=4: [polynomial of degree 31] for n>13

EXAMPLE

Some solutions for n=4 k=4

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

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

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

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

CROSSREFS

Column 1 is A000124

Sequence in context: A205744 A237859 A240338 * A223644 A223637 A223620

Adjacent sequences: A227100 A227101 A227102 * A227104 A227105 A227106

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Jul 01 2013

STATUS

approved

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Last modified February 3 14:36 EST 2023. Contains 360035 sequences. (Running on oeis4.)