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)

1, 4, 38, 820, 42928, 2352068, 273609756, 39956342600, 10520852944576

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