A205408 Number of (n+2) X 3 0..2 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly two ways, and new values 0..2 introduced in row major order.

468, 3868, 33322, 236576, 1820215, 14452683, 109757792, 844627201, 6555663807, 50395116296, 388310279461, 2998496455277, 23106198583152, 178125506630869, 1373888878002903, 10592170949339668, 81666691848271821, 629737361145882421

Offset: 1

Author

R. H. Hardin, Jan 26 2012

Keywords

• nonn

Comments

Column 1 of A205415.

Examples

			Some solutions for n=3
..0..0..0....0..0..0....0..0..1....0..0..1....0..0..0....0..0..0....0..1..2
..1..1..2....0..1..2....2..0..1....1..1..1....0..0..0....1..0..2....0..2..2
..0..0..0....0..1..2....1..0..0....0..1..1....1..1..2....0..1..0....0..1..2
..2..2..2....0..2..2....0..0..0....0..0..0....2..2..2....1..1..1....0..1..2
..1..2..1....0..2..2....2..1..0....0..2..2....2..0..2....0..0..0....1..1..1
		

Links

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

Crossrefs

Cf. A205415.

Formula

Empirical: a(n) = 3*a(n-1) +15*a(n-2) +210*a(n-3) -46*a(n-4) -1180*a(n-5) -8860*a(n-6) -9460*a(n-7) +35477*a(n-8) +165003*a(n-9) +271917*a(n-10) -292806*a(n-11) -1718502*a(n-12) -2698834*a(n-13) -1465296*a(n-14) +4872048*a(n-15) [phone]*a(n-16) [phone]*a(n-17) [phone]*a(n-18) [phone]*a(n-19) -115878688*a(n-20) -314261840*a(n-21) -579542448*a(n-22) -599435264*a(n-23) [phone]*a(n-24) [phone]*a(n-25) [phone]*a(n-26) [phone]*a(n-27) -5040264704*a(n-28) -21090059008*a(n-29) -30058399232*a(n-30) -12075326464*a(n-31) [phone]*a(n-32) [phone]*a(n-33) [phone]*a(n-34) -75591352320*a(n-35) -84606517248*a(n-36) [phone]*a(n-37) [phone]*a(n-38) [phone]*a(n-39).