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A218238 Hilltop maps: number of n X 4 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..3 n X 4 array. 1
15, 255, 4095, 65535, 1048545, 16776705, 268427265, 4294836225, 68717379375, 1099478066175, 17591648997375, 281466382974975, 4503462111871425, 72055393538292225, 1152886292586266625, 18446180616957722625 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A218242.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..88

FORMULA

Empirical: a(n) = 15*a(n-1) + 15*a(n-2) + 15*a(n-3) + 15*a(n-4) + 15*a(n-5) + 15*a(n-6) + 15*a(n-7).

Empirical g.f.: 15*x*(1 + x)^2*(1 + x^2)^2 / (1 - 15*x - 15*x^2 - 15*x^3 - 15*x^4 - 15*x^5 - 15*x^6 - 15*x^7). - Colin Barker, Jul 24 2018

EXAMPLE

Some solutions for n=3:

..0..1..1..0....1..1..1..0....1..0..1..0....0..0..0..1....0..1..1..1

..0..0..0..1....1..0..1..0....0..1..1..0....1..1..1..1....0..1..1..1

..0..1..1..1....0..1..0..1....1..1..0..1....0..1..1..1....0..1..1..0

CROSSREFS

Cf. A218242.

Sequence in context: A182607 A218284 A218634 * A015691 A145562 A027775

Adjacent sequences:  A218235 A218236 A218237 * A218239 A218240 A218241

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 24 2012

STATUS

approved

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Last modified February 25 11:19 EST 2021. Contains 341606 sequences. (Running on oeis4.)