A166766 Number of n X 4 1..2 arrays containing at least one of each value, and all equal values connected.

6, 56, 292, 1254, 4942, 18584, 67756, 241542, 846502, 2927816, 10023380, 34042358, 114900334, 385933816, 1291392908, 4308452150, 14341213590, 47651315192, 158111069492, 524063522870, 1735584459598, 5744207323976, 19002070568572, 62835884445574, 207725012781046, 686552300486040

Offset: 1

Author

R. H. Hardin, Oct 21 2009

Keywords

• nonn

Examples

			Some solutions for n=4
...1.1.1.1...2.2.1.1...2.2.2.2...1.1.2.2...2.2.2.2...2.1.1.1...2.2.2.2
...1.2.1.1...2.1.1.1...1.2.1.2...2.1.1.2...1.1.2.1...2.2.1.1...2.2.2.2
...1.2.1.2...2.1.1.1...1.2.1.1...2.1.2.2...1.1.1.1...2.2.1.1...1.2.2.1
...2.2.2.2...1.1.1.1...1.1.1.1...2.2.2.2...1.1.1.1...2.1.1.1...1.1.1.1
------
...2.2.2.2...2.2.2.2...2.2.1.1...1.1.2.1...2.1.1.1...1.1.1.1...1.1.2.2
...2.1.1.1...1.1.1.2...1.2.2.1...1.1.2.1...2.1.2.2...1.2.1.2...1.1.1.1
...1.1.1.1...1.1.2.2...1.2.1.1...1.1.1.1...2.1.2.2...1.2.2.2...1.1.1.1
...1.1.1.1...2.2.2.2...1.1.1.1...1.1.1.1...2.2.2.2...1.1.2.2...1.1.1.1
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..200
• Index entries for linear recurrences with constant coefficients, signature (10,-37,59,-27,-25,21,5,-4,-1).

Crossrefs

Twice row 4 of A378932.

Cf. A378934.

Formula

a(n) = 2*A378934(n). - Andrew Howroyd, Dec 12 2024

Extensions

a(16) onwards from Andrew Howroyd, Dec 12 2024