id:A140186 - OEIS Search Results

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Number of connected groupoids (categories all of whose morphisms are invertible) with n more morphisms than objects.

+0
3

2, 1, 2, 2, 1, 2, 3, 5, 2, 2, 2, 5, 2, 2, 3, 15, 1, 5, 2, 5, 3, 2, 3, 15, 3, 2, 6, 4, 2, 4, 7, 51, 1, 4, 3, 14, 1, 2, 4, 14, 1, 6, 4, 4, 3, 3, 6, 52, 2, 5, 2, 7, 1, 15, 4, 13, 3, 2, 2, 13, 4, 2, 18, 267, 1, 4, 3, 5, 1, 9, 7, 50, 2, 2, 4, 4, 2, 6, 8, 52, 15, 2, 3, 15, 1, 2, 3, 14, 1, 10, 3, 5, 4 (list; graph; listen)

	OFFSET	`0,1`
	COMMENT	`a(n) >= A000001(n+1) (number of groups of order n+1).`
	FORMULA	`a(0) = 2 and if n>0, a(n) = sum(A000001((n+k)/(k^2)),k^2\|n+k). (see formula for A140185)`
	CROSSREFS	`Cf. A140185, A140187, A140188.` `Sequence in context: A070080 A131400 A132749 this_sequence A078498 A131240 A107027` `Adjacent sequences: A140183 A140184 A140185 this_sequence A140187 A140188 A140189`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Jubin (benoit_jubin(AT)yahoo.fr), May 12 2008`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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