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 A058157 Triangle read by rows: T(n,k) is the number of labeled monoids of order n with k idempotents. 4
 1, 2, 2, 3, 18, 12, 16, 180, 288, 140, 30, 2640, 6540, 8380, 3020, 480, 119610, 238200, 421020, 372360, 100362, 840, 25196052, 13786290, 26803000, 36174600, 22822674, 4768624, 22080, 48687313640, 2254725312, 2358499080, 3849768160, 3859581096, 1826525120, 305498328 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..36. Index entries for sequences related to monoids FORMULA T(n,k) = A058158(n,k)*n. EXAMPLE Triangle begins: 1; 2, 2; 3, 18, 12; 16, 180, 288, 140; 30, 2640, 6540, 8380, 3020; ... CROSSREFS Row sums give A058153. Column 1: A034383. Main diagonal is A351731. Cf. A058137 (isomorphism classes), A058158, A058159 (commutative), A058166. Sequence in context: A049009 A101817 A058159 * A348667 A230504 A265806 Adjacent sequences: A058154 A058155 A058156 * A058158 A058159 A058160 KEYWORD nonn,tabl AUTHOR Christian G. Bower, Nov 14 2000 EXTENSIONS a(30)-a(36) from Andrew Howroyd, Feb 15 2022 STATUS approved

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Last modified September 18 02:51 EDT 2024. Contains 375995 sequences. (Running on oeis4.)