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A030270 Number of nonisomorphic and nonantiisomorphic reflexive transitive and cotransitive (complement is transitive) relations. +0
1
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; listen)
OFFSET

0,3
FORMULA

a(n) = (A001333(n) + A001333(floor((n+2)/2))) / 2.

CROSSREFS

Sequence in context: A026786 A027246 A090345 this_sequence A129757 A135019 A017921

Adjacent sequences: A030267 A030268 A030269 this_sequence A030271 A030272 A030273

KEYWORD

nonn,easy

AUTHOR

Christian G. Bower (bowerc(AT)usa.net)

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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