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A221405 Number of nX4 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, with every occupancy equal to zero or two 1
4, 44, 436, 4518, 47156, 492102, 5133044, 53529806, 558164472, 5819704716, 60677191216, 632619159318, 6595610902832, 68764677891112, 716926331557236, 7474513869766556, 77927543824707370, 812454058048811426 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A221408

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..94

FORMULA

Empirical: a(n) = 19*a(n-1) -110*a(n-2) +250*a(n-3) -446*a(n-4) +939*a(n-5) -1112*a(n-6) -343*a(n-7) -822*a(n-8) +692*a(n-9) +1957*a(n-10) +2810*a(n-11) -1975*a(n-12) -59*a(n-13) -2679*a(n-14) +738*a(n-15) +1088*a(n-16) +1258*a(n-17) -418*a(n-18) -562*a(n-19) +192*a(n-20) +336*a(n-21) +32*a(n-22) -32*a(n-23)

EXAMPLE

Some solutions for n=3

..0..2..2..0....0..2..0..2....2..2..0..2....2..2..0..2....0..2..0..0

..2..2..0..0....0..2..0..2....0..0..0..2....0..2..0..0....2..0..0..2

..0..0..2..2....2..0..0..2....2..2..0..0....2..0..2..0....2..2..2..0

CROSSREFS

Sequence in context: A002754 A187870 A216272 * A105038 A002278 A112897

Adjacent sequences:  A221402 A221403 A221404 * A221406 A221407 A221408

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 15 2013

STATUS

approved

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Last modified May 12 07:28 EDT 2021. Contains 343821 sequences. (Running on oeis4.)