

A133262


Number of twodimensional simple permutations.


0



1, 4, 8, 172, 5204, 222716, 12509188, 889421564, 78097622276, 8312906703868, 1056520142488580, 158263730949406716, 27626236450406776836, 5563092167972597137404, 1280742543230231763615748, 334405228960123174787678204, 98317121153947856929753989124, 32339023133437156084762282819580, 11831483864832785151824395066146820, 4789379698138059405310741712024371196
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OFFSET

1,2


COMMENTS

A twodimensional permutation of n is a vector of three permutations, with the first element being the identity permutation. For example, ( (1 2 3) (1 3 2) (3 1 2) ) is a twodimensional permutation of 3. The example is a simple twodimensional permutation because none of the intervals of length 2 in the permutations is common among all three. On the other hand, ( (1 2 3) (1 3 2) (2 3 1) ) is not simple because the intervals covering 2 and 3 are common among all three permutations.


LINKS



CROSSREFS



KEYWORD

nonn


AUTHOR

Hao Zhang and Daniel Gildea (zhanghao(AT)cs.rochester.edu), Oct 15 2007


EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Feb 10 2008


STATUS

approved



