A210904 Number of n X n 0..2 symmetric matrices with every element equal to zero, one, two or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

1, 5, 108, 7722, 1640736, 1033777404, 1931855614272, 10707730229352132, 176032647122454516348, 8583448868806218541129800, 1241375815868250678950006865216, 532497522393110319522129344363284548

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..16

Example

Some solutions for n=4
..0..1..2..0....0..0..0..1....0..1..1..0....0..1..1..0....0..1..1..2
..1..0..1..0....0..1..2..0....1..0..1..0....1..1..0..2....1..2..1..0
..2..1..2..2....0..2..1..0....1..1..2..1....1..0..0..1....1..1..1..0
..0..0..2..2....1..0..0..2....0..0..1..0....0..2..1..1....2..0..0..2

Crossrefs

Sequence in context: A336436 A318986 A220549 * A306990 A048564 A139971

Adjacent sequences: A210901 A210902 A210903 * A210905 A210906 A210907

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved