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A092284
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Number of nonterminal symbols in a certain ``divide-and-conquer'' context-free grammar in Chomsky normal form that generates all permutations of n symbols.
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0
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1, 3, 7, 11, 26, 42, 99, 107, 382, 428, 1156, 1223, 4525, 4903, 14811, 14827, 58022, 61236, 201420, 201611
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| P. R. J. Asveld, Generating all permutations by context-free grammars in Chomsky normal form, Theoretical Computer Science 354 (2006) 118-130.
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FORMULA
| a(n) = Sum(k=1..n, t(n, k)), where t(n, k) is the n-th row of the Pascal-like triangle of A090349.
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EXAMPLE
| a(4)=4+6+0+1=11; cf. the example grammar of A090349.
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CROSSREFS
| Cf. A090349.
Sequence in context: A188132 A139814 A099902 * A024459 A001645 A103798
Adjacent sequences: A092281 A092282 A092283 * A092285 A092286 A092287
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KEYWORD
| nonn
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AUTHOR
| Peter R. J. Asveld (infprja(AT)cs.utwente.nl), Jan 30 2004
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