A220749 Equals one maps: number of n X 4 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal and vertical neighbors in a random 0..3 n X 4 array.

8, 176, 3778, 65084, 1048014, 16776688, 268434892, 4294966696, 68719476100, 1099511627104, 17592186043708, 281474976709912, 4503599627369716, 72057594037927120, 1152921504606846124, 18446744073709550728

Offset

1,1

Comments

Column 4 of A220751.

Links

R. H. Hardin, Table of n, a(n) for n = 1..38

Formula

Empirical: a(n) = 18*a(n-1) - 33*a(n-2) + 16*a(n-3) for n>8.

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

G.f.: 2*x*(4 + 16*x + 437*x^2 + 1380*x^3 - 820*x^4 - 120*x^5 - 1187*x^6 + 560*x^7) / ((1 - x)^2*(1 - 16*x)).

a(n) = -312 + 16^n - 36*n for n>5.

(End)

Example

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

Crossrefs

Cf. A220751.

Sequence in context: A027464 A220966 A220544 * A221631 A064342 A251578

Adjacent sequences: A220746 A220747 A220748 * A220750 A220751 A220752

Keyword

nonn

Author

R. H. Hardin, Dec 18 2012

Status

approved