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A228502 Number of n X 4 binary arrays with top left value 1 and no two ones adjacent horizontally, vertically, diagonally or antidiagonally. 1
3, 5, 29, 87, 358, 1252, 4749, 17285, 64235, 236211, 873250, 3219652, 11886927, 43856285, 161862005, 597285195, 2204231074, 8134165648, 30017792409, 110774426621, 408792375587, 1508567655759, 5567079710158, 20544224979592 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + 7*a(n-2) - 2*a(n-3) - 3*a(n-4).
Empirical g.f.: x*(1 - x)*(3 + 2*x) / (1 - 2*x - 7*x^2 + 2*x^3 + 3*x^4). - Colin Barker, Sep 12 2018
EXAMPLE
Some solutions for n=4:
..1..0..1..0....1..0..1..0....1..0..0..0....1..0..0..1....1..0..1..0
..0..0..0..0....0..0..0..0....0..0..1..0....0..0..0..0....0..0..0..0
..0..0..1..0....0..0..0..0....0..0..0..0....0..0..1..0....0..0..0..0
..1..0..0..0....0..0..0..1....1..0..0..1....1..0..0..0....1..0..1..0
CROSSREFS
Column 4 of A228506.
Sequence in context: A128551 A154942 A240110 * A215663 A092330 A176951
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 23 2013
STATUS
approved

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Last modified June 13 07:34 EDT 2024. Contains 373366 sequences. (Running on oeis4.)