A058160 - OEIS

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A058160

Triangle read by rows: T(n,k) is the number of labeled commutative monoids of order n with k idempotents and a fixed identity.

1, 1, 1, 1, 6, 2, 4, 45, 36, 9, 6, 408, 648, 348, 76, 60, 7195, 13500, 11790, 5280, 1065, 120, 200016, 369930, 425280, 293640, 118890, 22566, 1920, 13811077, 14716716, 18035745, 16347660, 9953265, 3750516, 674611, 7560, 3405271616, 1024787568, 971651856, 999666920, 794967600, 445001424, 157962168, 27019896

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,5

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..55 (rows 1..10)

Index entries for sequences related to monoids

FORMULA

T(n, k) = A058159(n, k)/n.

EXAMPLE

Triangle begins:

1, 1;,

1, 6, 2;