A218283 Hilltop maps: number of n X 3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..4 n X 3 array.

7, 63, 511, 4091, 32739, 261905, 2095233, 16761837, 134094563, 1072755573, 8582037499, 68656243311, 549249492763, 4393992312383, 35151909460619, 281215043377605, 2249718488563135, 17997733040855701, 143981745385748627

Offset

1,1

Comments

Column 3 of A218288.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 7*a(n-1) +7*a(n-2) +7*a(n-3) +7*a(n-4) +7*a(n-5) +6*a(n-6) +12*a(n-7) +10*a(n-8) +48*a(n-9) +9*a(n-10) +9*a(n-11) +9*a(n-12) +9*a(n-13) +9*a(n-14) +5*a(n-15) +13*a(n-16) +11*a(n-17) -52*a(n-18) -64*a(n-19) -64*a(n-20) -64*a(n-21) -63*a(n-22) -59*a(n-23) -48*a(n-24) -38*a(n-25) +13*a(n-26) +41*a(n-27) +48*a(n-28) +48*a(n-29) +48*a(n-30) +46*a(n-31) +33*a(n-32) +15*a(n-33) +5*a(n-34) -5*a(n-35) -7*a(n-36) -7*a(n-37) -7*a(n-38) -7*a(n-39) -6*a(n-40) -2*a(n-41) +2*a(n-42) -a(n-44) -a(n-45) -a(n-46) -a(n-47) -a(n-48) -a(n-49).

Example

Some solutions for n=3
..0..0..1....0..1..0....1..1..1....1..0..0....0..1..0....0..1..1....0..1..1
..0..1..0....0..1..1....0..0..1....0..1..0....0..1..1....1..1..0....0..1..1
..0..0..0....1..0..0....1..0..1....0..0..0....0..1..1....1..0..0....0..0..0

Crossrefs

Cf. A218288.

Sequence in context: A218367 A218314 A218633 * A218237 A024088 A291034

Adjacent sequences: A218280 A218281 A218282 * A218284 A218285 A218286

Keyword

nonn

Author

R. H. Hardin, Oct 25 2012

Status

approved