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A052884
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A simple grammar.
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0
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0, 1, 2, 6, 20, 73, 278, 1106, 4519, 18908, 80530, 348144, 1523492, 6736163, 30046395, 135041458, 610954709, 2780185203, 12716659506, 58434130086, 269618874220
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 857
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MAPLE
| spec := [S, {B=Prod(Z, C), S=Sequence(B, 1 <= card), C= Set(S)}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A150138 A148481 A150139 * A150140 A061396 A192497
Adjacent sequences: A052881 A052882 A052883 * A052885 A052886 A052887
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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