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A052870
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A simple grammar.
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1
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1, 1, 2, 6, 15, 44, 128, 386, 1179, 3679, 11601, 37030, 119262, 387325, 1266647, 4168264, 13791565, 45856091, 153134306, 513403575, 1727395042
(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 841
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MAPLE
| spec := [S, {C=Sequence(Z, 1 <= card), S=PowerSet(B), B=Prod(C, S)}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A148438 A148439 A151515 * A001444 A138574 A045628
Adjacent sequences: A052867 A052868 A052869 * A052871 A052872 A052873
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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