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A079198 Number of associative non-commutative closed binary operations on a set of order n. 7
0, 2, 50, 2352, 153002, 15876046, 7676692858 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) + A079192(n) + A079195(n) + A023815(n) = A002489(n).

Each a(n) is equal to the sum of the products of each element in row n of A079200 and the corresponding element of A079210.

Since this is the number on labeled noncommutative semigroups on an n-set, a(n) = A023814(n)-A023815(n). - Stanislav Sykora, Apr 03 2016

LINKS

Table of n, a(n) for n=1..7.

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

Index entries for sequences related to semigroups

CROSSREFS

Cf. A023814, A023815, A079192, A079195, A079199, A079200.

Sequence in context: A088920 A278456 A231043 * A274485 A210919 A210924

Adjacent sequences:  A079195 A079196 A079197 * A079199 A079200 A079201

KEYWORD

nonn,more

AUTHOR

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

EXTENSIONS

a(5)-a(7) added by Stanislav Sykora, Apr 03 2016

STATUS

approved

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Last modified March 25 01:30 EDT 2017. Contains 284036 sequences.