login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A184541
Number of (n+2) X 4 binary arrays with each 3 X 3 subblock having rows and columns in lexicographically nondecreasing order.
1
89, 193, 340, 537, 792, 1114, 1513, 2000, 2587, 3287, 4114, 5083, 6210, 7512, 9007, 10714, 12653, 14845, 17312, 20077, 23164, 26598, 30405, 34612, 39247, 44339, 49918, 56015, 62662, 69892, 77739, 86238, 95425, 105337, 116012, 127489, 139808, 153010
OFFSET
1,1
COMMENTS
Column 2 of A184548.
LINKS
FORMULA
Empirical: a(n) = (1/24)*n^4 + (3/4)*n^3 + (383/24)*n^2 + (201/4)*n + 22.
Conjectures from Colin Barker, Apr 12 2018: (Start)
G.f.: x*(89 - 252*x + 265*x^2 - 123*x^3 + 22*x^4) / (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>5.
(End)
EXAMPLE
Some solutions for 6 X 4:
..0..0..0..0....0..0..0..1....0..0..0..0....0..0..0..1....0..0..0..1
..0..0..0..1....0..0..0..1....0..0..0..1....0..0..0..1....0..0..1..1
..0..0..0..1....0..0..0..1....0..0..0..1....0..0..0..1....0..1..1..1
..0..0..0..1....0..0..0..1....0..0..1..1....0..0..0..1....0..1..1..1
..0..0..1..0....0..0..1..0....0..1..0..0....0..0..0..1....1..1..1..1
..0..1..1..0....0..0..1..1....1..1..0..0....0..0..0..1....1..1..1..1
CROSSREFS
Cf. A184548.
Sequence in context: A044421 A044802 A142499 * A141953 A142625 A054694
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 16 2011
STATUS
approved