A058129 - OEIS

A058129

Number of nonisomorphic monoids (semigroups with identity) of order n.

0, 1, 2, 7, 35, 228, 2237, 31559, 1668997

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..8.

Remigiusz Durka and Kamil Grela, On the number of possible resonant algebras, arXiv:1911.12814 [hep-th], 2019.

Najwa Ghannoum, Investigation of finite categories, Doctoral thesis, Univ. Côte d'Azur (France); Univ. Libanaise (Lebanon), tel-0394832 [math.CT], 2022.

Eric Postpischil, Posting to sci.math newsgroup, May 21 1990

Clayton Cristiano Silva, Irreducible Numerical Semigroups, University of Campinas, São Paulo, Brazil (2019).

Index entries for sequences related to monoids

FORMULA

a(n) = 2*A058133(n) - A058132(n).

a(n) < A027851(n) except for equality iff n = 1. - M. F. Hasler, Dec 10 2018

CROSSREFS

Cf. A058132, A058133.

Cf. A027851 (number of all nonisomorphic semigroups).

Sequence in context: A014307 A000154 A003713 * A101514 A247240 A266356

Adjacent sequences: A058126 A058127 A058128 * A058130 A058131 A058132

KEYWORD

nonn,hard,more

AUTHOR

Christian G. Bower, Nov 13 2000

EXTENSIONS

a(8) from Christian G. Bower, Dec 26 2006

a(0) = 0 prepended by M. F. Hasler, Dec 10 2018

STATUS

approved