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Search: id:A158278
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| A158278 |
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Number of symmetric numerical semigroups with Frobenius number 2*n-1; that is, symmetric numerical semigroups for which the largest integer not belonging to them is 2*n-1. |
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+0
1
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| 1, 1, 2, 3, 3, 6, 8, 7, 15, 20, 18, 36, 44, 45, 83, 109, 101, 174, 246, 227
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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a(n)=A158206(2*n-1)
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REFERENCES
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J. C. Rosales, P. A. Garcia-Sanchez, J. I. Garcia-Garcia and J. A. Jimenez-Madrid, Fundamental gaps in numerical semigroups, Journal of Pure and Applied Algebra 189 (2004) 301-313.
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LINKS
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S. R. Finch, Monoids of natural numbers
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EXAMPLE
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a(3)=2: the only 2 symmetric semigroups with Frobenius number 5=2*3-1 are generated by {3, 4} and {2, 7}.
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CROSSREFS
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Cf. A124506, A158206
Sequence in context: A091606 A027037 A020878 this_sequence A027100 A060840 A074717
Adjacent sequences: A158275 A158276 A158277 this_sequence A158279 A158280 A158281
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KEYWORD
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nonn
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AUTHOR
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S. R. Finch (Steven.Finch(AT)inria.fr), Mar 15 2009
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