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A238189
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Number T(n,k) of equivalence classes of ways of placing k 2 X 2 tiles in an n X 4 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=2, 0<=k<=n-n%2, read by rows.
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21
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1, 2, 1, 1, 2, 2, 1, 4, 7, 3, 1, 1, 4, 13, 10, 4, 1, 6, 23, 33, 22, 6, 1, 1, 6, 34, 68, 72, 30, 6, 1, 8, 49, 139, 204, 145, 54, 8, 1, 1, 8, 65, 230, 467, 476, 269, 70, 9, 1, 10, 85, 377, 961, 1348, 1080, 472, 111, 12, 1, 1, 10, 106, 552, 1767, 3188, 3454, 2156
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OFFSET
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2,2
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LINKS
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EXAMPLE
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The first 10 rows of T(n,k) are:
k 0 1 2 3 4 5 6 7 8 9 10
n
2 1 2 1
3 1 2 2
4 1 4 7 3 1
5 1 4 13 10 4
6 1 6 23 33 22 6 1
7 1 6 34 68 72 30 6
8 1 8 49 139 204 145 54 8 1
9 1 8 65 230 467 476 269 70 9
10 1 10 85 377 961 1348 1080 472 111 12 1
11 1 10 106 552 1767 3188 3454 2156 779 140 12
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PROG
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(C++) See Gribble link.
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CROSSREFS
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Cf. A034851, A226048, A102541, A226290, A238009, A228570, A225812, A238190, A228572, A228022, A231145, A231473, A231568, A232440, A228165, A238550, A238551, A238552, A228166, A238555, A238556, A228167, A238557, A238558, A238559, A228168, A238581, A238582, A238583, A228169, A238586, A238592.
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KEYWORD
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tabf,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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