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 A202902 Number of nX4 0..1 arrays with every one equal to some NW, E or S neighbor. 1
 1, 40, 494, 4892, 51068, 538672, 5654616, 59369072, 623600944, 6549786560, 68792261728, 722531010240, 7588808329152, 79705877679872, 837157507203456, 8792735883863808, 92350844763980544, 969968692011129856 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 Robert Israel, Maple-assisted proof of formula FORMULA Empirical: a(n) = 16*a(n-1) -76*a(n-2) +272*a(n-3) -1060*a(n-4) +2704*a(n-5) -5184*a(n-6) +9920*a(n-7) -11904*a(n-8) +9472*a(n-9) -7168*a(n-10) +4096*a(n-11) -1024*a(n-12). Empirical formula verified by Robert Israel, May 09 2018 (see link). EXAMPLE Some solutions for n=5 ..1..1..1..0....1..0..1..1....0..0..0..0....1..0..0..0....0..1..1..1 ..0..1..1..0....1..0..1..1....0..1..1..0....1..1..1..0....1..1..0..1 ..0..1..1..1....1..0..1..0....1..0..1..0....1..1..1..0....0..1..1..1 ..1..0..1..1....1..1..1..1....1..0..0..0....0..1..0..0....1..1..0..1 ..1..1..0..0....0..1..0..0....1..1..0..0....1..1..1..0....0..1..0..0 MAPLE f:= gfun:-rectoproc({a(n) = 16*a(n-1) -76*a(n-2) +272*a(n-3) -1060*a(n-4) +2704*a(n-5) -5184*a(n-6) +9920*a(n-7) -11904*a(n-8) +9472*a(n-9) -7168*a(n-10) +4096*a(n-11) -1024*a(n-12), seq(a(i)=[1, 40, 494, 4892, 51068, 538672, 5654616, 59369072, 623600944, 6549786560, 68792261728, 722531010240][i], i=1..12)}, a(n), remember): map(f, [\$1..25]); # Robert Israel, May 09 2018 CROSSREFS Column 4 of A202906. Sequence in context: A186933 A271650 A177096 * A140045 A223162 A069079 Adjacent sequences: A202899 A202900 A202901 * A202903 A202904 A202905 KEYWORD nonn AUTHOR R. H. Hardin, Dec 25 2011 STATUS approved

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Last modified February 26 10:21 EST 2024. Contains 370342 sequences. (Running on oeis4.)