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A218811 Hilltop maps: number of 2Xn binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or antidiagonal neighbor in a random 0..3 2Xn array 1
1, 15, 61, 249, 993, 3969, 15871, 63467, 253797, 1014889, 4058377, 16228793, 64896323, 259509919, 1037738269, 4149747805, 16594171517, 66357412857, 265352580967, 1061102131539, 4243176114789, 16967776245057, 67851397847697 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 2 of A218810

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) +3*a(n-2) +3*a(n-3) +3*a(n-4) +3*a(n-5) +a(n-6) +5*a(n-7) +2*a(n-8) +2*a(n-9) +2*a(n-10) +2*a(n-11) +a(n-12) +a(n-13) -a(n-14) -a(n-15) -a(n-16) -a(n-17) -a(n-18) -a(n-19) for n>20

EXAMPLE

Some solutions for n=3

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

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

CROSSREFS

Sequence in context: A022288 A041432 A072201 * A219819 A157446 A220084

Adjacent sequences:  A218808 A218809 A218810 * A218812 A218813 A218814

KEYWORD

nonn

AUTHOR

R. H. Hardin Nov 06 2012

STATUS

approved

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Last modified May 28 22:08 EDT 2022. Contains 354122 sequences. (Running on oeis4.)