A030270 - OEIS

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A030270

Number of nonisomorphic and nonantiisomorphic reflexive transitive and cotransitive (complement is transitive) relations.

1, 1, 3, 5, 12, 24, 58, 128, 309, 717, 1731, 4109, 9920, 23780, 57410, 138192, 333625, 804457, 1942131, 4686341, 11313828, 27308256, 65927962, 159150320, 384222861, 927562581, 2239334163, 5406150125, 13051600952, 31509157004 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,3`
	FORMULA	`a(n) = (A001333(n) + A001333(floor((n+2)/2))) / 2.`
	CROSSREFS	`Sequence in context: A185087 A186334 A151524 * A129757 A135019 A141685` `Adjacent sequences: A030267 A030268 A030269 * A030271 A030272 A030273`
	KEYWORD	`nonn,easy`
	AUTHOR	`Christian G. Bower (bowerc(AT)usa.net)`

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Last modified February 15 15:20 EST 2012. Contains 205823 sequences.