A079195 - OEIS

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A079195

Number of non-associative commutative closed binary operations on a set of order n.

13

0, 0, 2, 666, 1047436, 30517547395, 21936950639192784, 459986536544739894613595, 324518553658426726783148869733112

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OFFSET

0,3

LINKS

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

C. van den Bosch, Closed binary operations on small sets

Index entries for sequences related to groupoids

FORMULA

A079192(n) + a(n) + A079198(n) + A023815(n) = A002489(n).

a(n) = Sum_{k>=1} A079197(n,k)*A079210(n,k).

a(n) = A023813(n) - A023815(n). - Andrew Howroyd, Jan 26 2022

CROSSREFS

Cf. A023813, A023815, A079192, A079196 (isomorphism classes), A079197, A079198.

Sequence in context: A046856 A156938 A285221 * A120123 A140014 A188698

Adjacent sequences: A079192 A079193 A079194 * A079196 A079197 A079198

KEYWORD

nonn

AUTHOR

Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003

EXTENSIONS

a(0)=0 prepended and a(5)-a(8) added by Andrew Howroyd, Jan 26 2022

STATUS

approved