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A048019 Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= (n-2)/3. 0
0, 0, 0, 0, 4, 10, 20, 41, 77, 140, 252, 505, 1000, 1780, 3652, 7305, 12545, 25805, 52325, 88634, 184736, 379676, 636524, 1334942, 2764139, 4594244, 9685364, 20191604, 33355944, 70639794, 148064400, 243374923, 517215283 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..33.

CROSSREFS

Sequence in context: A100354 A275358 A048008 * A189586 A019498 A237626

Adjacent sequences:  A048016 A048017 A048018 * A048020 A048021 A048022

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified January 23 03:02 EST 2021. Contains 340384 sequences. (Running on oeis4.)