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A232997
Number of tilings of a fortress (or Penta-Aztec-Diamond) of order n.
0
1, 1, 5, 50, 625, 15625, 1953125, 488281250, 152587890625, 95367431640625, 298023223876953125, 1862645149230957031250, 14551915228366851806640625, 227373675443232059478759765625, 17763568394002504646778106689453125, 2775557561562891351059079170227050781250
OFFSET
0,3
COMMENTS
The Lai (2013) article contains many other sequences which should be added to the OEIS (e.g. the sequences in Theorems 15, 18, 21, 22 and Corollary 20).
LINKS
Tri Lai, New aspects of regions whose tilings are enumerated by perfect powers, Electronic Journal of Combinatorics, 20(4), 2013, #P31. See Th. 8.
MAPLE
f:=n-> if (n mod 2) = 0 then 5^((n/2)^2) elif (n mod 4) = 1 then 5^((n^2-1)/4) else 2*5^((n^2-1)/4); fi;
[seq(f(n), n=0..30)];
CROSSREFS
Sequence in context: A233068 A237020 A156058 * A357405 A234464 A047736
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 17 2013
STATUS
approved