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A058116 Triangle: Number of commutative semigroups of order n with k idempotents. 4
1, 2, 1, 5, 5, 2, 16, 23, 14, 5, 62, 106, 93, 49, 15, 342, 544, 582, 422, 200, 53, 3435, 3380, 3773, 3360, 2178, 943, 222 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..28.

Index entries for sequences related to semigroups

EXAMPLE

1;

2, 1;

5, 5, 2;

16, 23, 14, 5;

62, 106, 93, 49, 15;

...

CROSSREFS

Row sums give A001426. Main diagonal: A006966(n+1). Column 1: A058117.

Sequence in context: A248905 A118244 A108410 * A058118 A124226 A248797

Adjacent sequences:  A058113 A058114 A058115 * A058117 A058118 A058119

KEYWORD

nonn,tabl,hard,more

AUTHOR

Christian G. Bower, Nov 09 2000

STATUS

approved

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Last modified October 24 01:08 EDT 2018. Contains 316541 sequences. (Running on oeis4.)