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A233343
Number of tilings of a 7 X 3n rectangle using 7n trominoes of any shape.
3
1, 441, 614581, 1064557805, 1949314526229, 3619365754064658, 6743148875847013949, 12573396789552627635974, 23449283563696481324707977, 43734844458505039459034141789, 81570040233489554572733439665568, 152137050633841639720340771054558899
OFFSET
0,2
LINKS
Wikipedia, Tromino
CROSSREFS
Trisection of column k=7 of A233320.
Sequence in context: A264277 A268874 A264223 * A110996 A013769 A013899
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 07 2013
STATUS
approved