A221022 Equals one maps: number of n X 4 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, vertical and antidiagonal neighbors in a random 0..3 n X 4 array.

8, 168, 3474, 62944, 1038208, 16735744, 268269568, 4294303744, 68716822528, 1099501010944, 17592143577088, 281474806841344, 4503598947893248, 72057591320018944, 1152921493735211008, 18446744030223007744

Offset

1,1

Comments

Column 4 of A221024.

Links

R. H. Hardin, Table of n, a(n) for n = 1..55

Formula

Empirical: a(n) = 20*a(n-1) -64*a(n-2) for n>5.

Conjectures from Colin Barker, Aug 03 2018: (Start)

G.f.: 2*x*(4 + 4*x + 313*x^2 + 2108*x^3 + 832*x^4) / ((1 - 4*x)*(1 - 16*x)).

a(n) = 16^n - 81*2^(2*n-3) for n>3.

(End)

Example

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

Crossrefs

Cf. A221024.

Sequence in context: A294512 A090228 A220808 * A039699 A307347 A253974

Adjacent sequences: A221019 A221020 A221021 * A221023 A221024 A221025

Keyword

nonn

Author

R. H. Hardin, Dec 28 2012

Status

approved