A231950 Number of (n+1)X(1+1) 0..1 arrays with every element equal to some horizontal, vertical, diagonal or antidiagonal neighbor, with top left element zero

4, 18, 64, 236, 888, 3336, 12512, 46928, 176032, 660320, 2476928, 9291200, 34852224, 130734208, 490397184, 1839529216, 6900259328, 25883567616, 97091868672, 364201376768, 1366156040192, 5124588881920, 19222848954368, 72106842214400

Offset

1,1

Comments

Column 1 of A231957

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -2*a(n-2) +4*a(n-3)

Example

Some solutions for n=7
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..1
..0..0....0..0....1..0....0..1....0..0....0..1....0..1....1..0....1..0....0..1
..0..1....0..0....1..0....1..0....0..0....0..1....1..1....1..1....0..1....0..0
..0..1....1..0....1..0....1..0....1..0....0..0....0..1....0..1....0..1....1..0
..1..1....0..1....0..0....1..0....0..1....0..0....0..1....0..1....1..0....0..1
..0..1....1..0....0..1....0..1....0..1....1..1....1..0....1..1....0..0....0..1
..1..0....0..1....1..1....1..0....1..0....0..1....1..0....0..0....1..0....1..0
..0..1....1..1....0..0....0..0....0..0....0..1....0..1....1..1....1..0....0..0

Crossrefs

Sequence in context: A362316 A255611 A022728 * A246134 A115112 A171074

Adjacent sequences: A231947 A231948 A231949 * A231951 A231952 A231953

Keyword

nonn

Author

R. H. Hardin, Nov 15 2013

Status

approved