A211101 1/4 the number of (n+1) X (n+1) 0..3 symmetric matrices with every 2 X 2 subblock having two distinct values.

9, 123, 2775, 104115, 6789723, 768377817, 153389832249, 54108183764037, 33918021524578413, 37878314811930907251, 75553188571072163648355, 269703947104281265724134083, 1725747428908865992844982156771

Offset

1,1

Links

Table of n, a(n) for n=1..13.

Example

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

Crossrefs

Sequence in context: A365848 A295095 A295549 * A269627 A209504 A320529

Adjacent sequences: A211098 A211099 A211100 * A211102 A211103 A211104

Keyword

nonn

Author

R. H. Hardin, Mar 31 2012

Status

approved