A221405 - OEIS

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

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