A072771 - OEIS

A072771

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

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, 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, 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

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OFFSET

1,7

COMMENTS

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).

LINKS

Table of n, a(n) for n=1..97.

A. Karttunen, Gatomorphisms (with the complete Scheme source)

CROSSREFS

Sequence in context: A208150 A045830 A078771 * A347715 A356305 A292247

Adjacent sequences: A072768 A072769 A072770 * A072772 A072773 A072774

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jun 12 2002

STATUS

approved