A079223 - OEIS

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A079223

Number of Catalan objects fixed by two-fold application of the Catalan bijections A057511/A057512 (Deep rotation of general parenthesizations/plane trees).

8

1, 1, 2, 5, 11, 26, 66, 161, 420, 1093, 2916, 7819, 21304, 58321, 161233, 448090, 1253252, 3521389, 9941693, 28175716, 80152141, 228747967, 654817275, 1879602446, 5408974390, 15601662378, 45098766532, 130624550412

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..27.

FORMULA

a(n) = A079216(n, 2)

MAPLE

A079223 := n -> A079216bi(n, 2);

CROSSREFS

The second row of A079216. The leftmost edge of the triangle A079218 and also its row sums shifted by one. Occurs for first time in A073202 as row 245. Cf. A057546, A079224, A079225, A079226, A079227.

Sequence in context: A025245 A300125 A307576 * A095892 A239311 A319760

Adjacent sequences: A079220 A079221 A079222 * A079224 A079225 A079226

KEYWORD

nonn

AUTHOR

Antti Karttunen Jan 03 2002

STATUS

approved