A038020 - OEIS

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A038020

Triangle: T(n,k), k<=n: groupoids with a nontrivial symmetry with n elements and k idempotents.

0, 0, 0, 2, 0, 2, 9, 54, 0, 30, 15376, 12664, 14304, 4096, 3187 (list; table; graph; refs; listen; history; internal format)

	OFFSET	`0,4`
	LINKS	`Index entries for sequences related to groupoids`
	FORMULA	`Difference of A038018 and A038019.`
	CROSSREFS	`Cf. A001329, A030248, A030251, A030271.` `Sequence in context: A137302 A091518 A096734 * A107094 A122496 A177113` `Adjacent sequences: A038017 A038018 A038019 * A038021 A038022 A038023`
	KEYWORD	`nonn,tabl`
	AUTHOR	`Christian G. Bower (bowerc(AT)usa.net), May 15 1998.`

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Last modified February 15 07:42 EST 2012. Contains 205717 sequences.