The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A210921 Number of n X n 0..3 symmetric matrices with every element equal to zero or two horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order. 0
 1, 3, 39, 2107, 277902, 87883641, 66460660741, 120226326939778, 520179215730042235, 5383068220104980704743, 133236771262960489496028245 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE Some solutions for n=4 ..0..1..0..3....0..0..1..1....0..1..1..1....0..1..0..1....0..1..2..3 ..1..2..1..2....0..0..1..1....1..1..0..1....1..0..1..2....1..0..3..1 ..0..1..2..3....1..1..2..0....1..0..1..1....0..1..2..0....2..3..0..0 ..3..2..3..1....1..1..0..1....1..1..1..2....1..2..0..2....3..1..0..0 CROSSREFS Sequence in context: A084881 A193122 A015017 * A290516 A210925 A300046 Adjacent sequences: A210918 A210919 A210920 * A210922 A210923 A210924 KEYWORD nonn AUTHOR R. H. Hardin, Mar 29 2012 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 4 22:05 EST 2023. Contains 360082 sequences. (Running on oeis4.)