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A178015
Number of permutations of 2 copies of 1..n with no element e[i>=2]<e[1+floor((i-2)/5)] (5-way heap)
0
1, 3, 30, 246, 5400, 134550, 5380020, 379593000, 18277228800, 1895009299200, 171982733220000, 21945548042928000
OFFSET
1,2
CROSSREFS
Simple 2-way heap A056971
Sequence in context: A051133 A332426 A043030 * A120689 A359614 A180426
KEYWORD
nonn
AUTHOR
R. H. Hardin May 17 2010
STATUS
approved