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Search: id:A079209
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| A079209 |
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Number of isomorphism classes of associative commutative non-anti-associative non-anti-commutative closed binary operations on a set of order n, listed by class size. |
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+0
9
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| 0, 0, 3, 0, 0, 3, 9, 0, 0, 0, 3, 0, 0, 16, 39
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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A079202(n)+A079203(n)+A079204(n)+A079205(n)+A079197(n)+A079207(n)+A079208(n)+A079209(n)+A063524(n)=A079171(n)
Elements per row: 1,2,4,8,16,30,... (given by A027423, number of positive divisors of n!)
First four rows: 0; 0,3; 0,0,3,9; 0,0,0,3,0,0,16,39
A079244(x) is equal to the sum of the products of each element in row x of this sequence and the corresponding element of A079210.
The sum of each row x of this sequence is given by A079245(x).
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LINKS
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C. van den Bosch, Closed binary operations on small sets
Index entries for sequences related to semigroups
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CROSSREFS
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Cf. A079202, A079203, A079204, A079205, A079197, A079207, A079208, A079244, A079245.
Sequence in context: A050452 A151665 A079201 this_sequence A021773 A133109 A130208
Adjacent sequences: A079206 A079207 A079208 this_sequence A079210 A079211 A079212
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KEYWORD
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nonn,tabf
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AUTHOR
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Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003
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