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A048021 Number of nonempty subsets of {1,2,...,n} in which exactly 1/5 of the elements are <= (n-2)/3. 0
0, 0, 0, 0, 1, 5, 15, 30, 70, 141, 213, 405, 765, 1110, 2310, 4954, 7435, 16575, 35945, 52871, 113815, 240385, 346745, 744345, 1595433, 2299998, 5036862, 10959446, 15770601, 34636245, 75326163, 107787262, 236331302, 514828047 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

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

CROSSREFS

Sequence in context: A246817 A010898 A048065 * A225325 A133268 A056108

Adjacent sequences:  A048018 A048019 A048020 * A048022 A048023 A048024

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified December 1 11:35 EST 2020. Contains 338833 sequences. (Running on oeis4.)