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A052829
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A simple grammar.
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0
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0, 1, 2, 4, 10, 25, 69, 197, 583, 1762, 5441, 17042, 54072, 173334, 560659, 1827306, 5995570, 19787135, 65643226, 218777532, 732181107
(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 794
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FORMULA
| G.f.: (x/(1-x))*Product((1+x)^a(k), k=1..infinity). - Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 22 2004
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MAPLE
| spec := [S, {B=Sequence(Z, 1 <= card), C=PowerSet(S), S=Prod(C, B)}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Cf. A052870 (first differences).
Sequence in context: A191768 A027432 A032128 * A001998 A005817 A152958
Adjacent sequences: A052826 A052827 A052828 * A052830 A052831 A052832
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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