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A058122 Number of self-converse idempotent semigroups of order n. 2
1, 1, 1, 2, 6, 19, 68, 285 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..7.

Index entries for sequences related to semigroups

CROSSREFS

Main diagonal of A058118.

Sequence in context: A150103 A150104 A145868 * A150105 A150106 A150107

Adjacent sequences:  A058119 A058120 A058121 * A058123 A058124 A058125

KEYWORD

nonn,hard

AUTHOR

Christian G. Bower, Nov 10 2000

STATUS

approved

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Last modified October 20 16:06 EDT 2018. Contains 316390 sequences. (Running on oeis4.)