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A178017 Number of permutations of 3 copies of 1..n with no element e[i>=2]<e[1+floor((i-2)/2)] (2-way heap) 0
1, 4, 38, 820, 42928, 2352068, 273609756, 39956342600, 10520852944576 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..9.

CROSSREFS

Simple 2-way heap A056971

Sequence in context: A084286 A001187 A093377 * A131591 A030259 A218710

Adjacent sequences:  A178014 A178015 A178016 * A178018 A178019 A178020

KEYWORD

nonn

AUTHOR

R. H. Hardin May 17 2010

STATUS

approved

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Last modified April 19 01:29 EDT 2019. Contains 322237 sequences. (Running on oeis4.)