login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A226429 Number of numerical semigroups S of genus 3^n having a minimal generating set of cardinality 2. 0
2, 3, 4, 4, 5, 7, 8, 9, 8, 9, 11, 13, 11, 15, 16, 14, 14, 18, 20, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Shalom Eliahou and Jorge Ramírez Alfonsín, Two-generator numerical semigroups and Fermat and Mersenne numbers, SIAM J. Discrete Math., 25(2), 2011, 622-630.
FORMULA
a(n) = n + 1 if 2*3^n - 1 is prime.
a(n) ~ n + 1.
CROSSREFS
Sequence in context: A036416 A084618 A075518 * A036820 A017829 A017843
KEYWORD
nonn,more
AUTHOR
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 10:22 EDT 2024. Contains 371268 sequences. (Running on oeis4.)