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A178009
Number of permutations of 1..n with no element e[i>=2]<e[1+floor((i-2)/4)] (4-way heap).
4
1, 1, 1, 2, 6, 24, 60, 240, 1260, 8064, 36288, 241920, 1995840, 19160064, 124540416, 1162377216, 13076743680, 167382319104, 1422749712384, 17072996548608, 243290200817664, 3892643213082624, 34060628114472960, 428190753439088640, 6463004184721244160
OFFSET
0,4
LINKS
Wikipedia, D-ary heap
CROSSREFS
Simple 2-way heap A056971.
Column k=4 of A273693.
Sequence in context: A022917 A189855 A189566 * A357249 A107762 A253901
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 17 2010
EXTENSIONS
a(0), a(20)-a(24) from Alois P. Heinz, May 27 2016
STATUS
approved