A073431 - OEIS

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A073431

Number of separate orbits/cycles to which the Catalan bijections A069767/A069768 partition each A000108(n) structures encoded in the range [A014137(n-1)..A014138(n-1)] of the sequence A014486/A063171.

1, 1, 1, 2, 3, 6, 12, 28, 65, 160, 408, 1074, 2898, 7998, 22508, 64426, 187251, 551730, 1645840, 4964876, 15130808, 46545788, 144424944, 451715460

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..23.

FORMULA

a(0)=1, a(n) = (1/(2^(n-1))) * Sum_{i=1..(2^(n-1))} (Sum_{j=0..A007814(i)} A073346(n, j)) = (1/(2^(n-2))) * Sum_{i=1..(2^(n-1))} A073346(n, A007814(i)) - 1 = (1/2^n) * Sum_{i=0..n} (2^(n-i))*A073346(n, i) = Sum_{i=0..n} A074079(n, i)

MAPLE

A073431 := proc(n) local i; (1/2^n) * add((2^(n-i))*A073346bi(n, i), i=0..n); end;

CROSSREFS

Occurs for first time in A073201 as row 6 (and 8). Column sums of the square array A074079/Row sums of the triangle A074080.

Sequence in context: A006082 A122889 A014280 * A273873 A337717 A003317

Adjacent sequences: A073428 A073429 A073430 * A073432 A073433 A073434

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jul 31 2002

STATUS

approved