OFFSET
0,3
LINKS
S. Butler, J. Ekstrand, S. Osborne, TETRIS Tiling, AMS Spring Central Sectional, Iowa State University, April 27-28 2013
R. S. Harris, Counting Polyomino Tilings
Wikipedia, Tetromino
FORMULA
a(n) = A230031(2n,2n).
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Alois P. Heinz, Oct 17 2015
STATUS
approved