|
|
A068254
|
|
1/4 the number of colorings of an n X n square array with 4 colors.
|
|
3
|
|
|
1, 21, 2403, 1500183, 5110723191, 95013316876491, 9639473169171326643, 5336900216006709884938623, 16124704040675904181778734982451, 265865038636937159336134567410478299051
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
MATHEMATICA
|
A222444 = Cases[Import["https://oeis.org/A222444/b222444.txt", "Table"], {_, _}][[All, 2]];
a[n_] := A222444[[2 n^2 - 2 n + 1]];
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|