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A178022
Number of permutations of 4 copies of 1..n with no element e[i>=2]<e[1+floor((i-2)/2)] (2-way heap)
0
1, 7, 206, 18155, 3340366, 1345907216, 965180428296, 1192995518065240
OFFSET
1,2
CROSSREFS
Simple 2-way heap A056971
Sequence in context: A243144 A234619 A308614 * A157775 A300619 A275822
KEYWORD
nonn
AUTHOR
R. H. Hardin May 17 2010
STATUS
approved