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X-projection of the tabular N X N -> N bijection A072764 and Y-projection of its transpose A072766.
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%I #3 May 01 2014 02:47:42

%S 0,0,1,0,0,1,2,3,0,0,0,0,0,1,1,2,4,5,3,6,7,8,0,0,0,0,0,0,0,0,0,0,0,0,

%T 0,0,1,1,1,1,1,2,2,4,9,10,5,11,12,13,3,3,6,14,15,7,16,17,18,8,19,20,

%U 21,22,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0

%N X-projection of the tabular N X N -> N bijection A072764 and Y-projection of its transpose A072766.

%C This corresponds to Lisp/Scheme function 'car' computed with respect to the lexicographical ordering of parenthesizations/planar binary trees (A014486), i.e. with planar binary trees this is equal to extracting the left subtree (from the root), with general parenthesizations equal to taking the first sub-parenthesization of the top-level list and with general plane trees equal to taking the leftmost branch of the tree (at the root).

%H A. Karttunen, <a href="http://www.iki.fi/~kartturi/matikka/Nekomorphisms/gatomorf.htm">Gatomorphisms</a> (with the complete Scheme source)

%K nonn

%O 1,7

%A _Antti Karttunen_, Jun 12 2002