A047172 - OEIS

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A047172

Number of nonempty subsets of {1,2,...,n} in which exactly 1/3 of the elements are <= (n-1)/2.

0

0, 0, 1, 3, 6, 13, 21, 45, 70, 154, 235, 525, 791, 1793, 2681, 6153, 9150, 21206, 31401, 73359, 108262, 254607, 374715, 886171, 1301235, 3091971, 4531423, 10811671, 15818791, 37877401, 55339849, 132924649, 193962894, 467187454

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OFFSET

1,4

LINKS

Table of n, a(n) for n=1..34.

CROSSREFS

Sequence in context: A293822 A371917 A180750 * A034734 A329766 A019079

Adjacent sequences: A047169 A047170 A047171 * A047173 A047174 A047175

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved