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A058166 Triangle read by rows: T(n,k) = number of labeled semigroups of order n with k idempotents. 0
1, 4, 4, 24, 54, 35, 356, 1044, 1488, 604, 16585, 31620, 60900, 57900, 16727, 3461916, 1699290, 3345420, 4744380, 3128880, 681232, 6058301508, 265521354, 263429355, 439698420, 455785470, 222132666, 38187291 (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; 4,4; 24,54,35; 356,1044,1488,604; ...

CROSSREFS

Row sums give A023814.

Sequence in context: A131978 A049614 A269186 * A092897 A269152 A269097

Adjacent sequences:  A058163 A058164 A058165 * A058167 A058168 A058169

KEYWORD

nonn,tabl,hard

AUTHOR

Christian G. Bower, Nov 15 2000

STATUS

approved

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Last modified February 21 22:56 EST 2018. Contains 299427 sequences. (Running on oeis4.)