OFFSET
1,3
LINKS
CombOS - Combinatorial Object Server, Generate numerical semigroups
S. R. Finch, Monoids of natural numbers
S. R. Finch, Monoids of natural numbers, March 17, 2009. [Cached copy, with permission of the author]
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.
Clayton Cristiano Silva, Irreducible Numerical Semigroups, University of Campinas, São Paulo, Brazil (2019).
FORMULA
a(n) = A158206(2*n-1).
EXAMPLE
a(3)=2: the only 2 symmetric semigroups with Frobenius number 5=2*3-1 are generated by {3, 4} and {2, 7}.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Steven Finch, Mar 15 2009
STATUS
approved