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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..491

Wikipedia, D-ary heap

CROSSREFS

Simple 2-way heap A056971.

Column k=4 of A273693.

Sequence in context: A022917 A189855 A189566 * A357249 A107762 A253901

Adjacent sequences:  A178006 A178007 A178008 * A178010 A178011 A178012

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

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Last modified October 3 17:49 EDT 2022. Contains 357237 sequences. (Running on oeis4.)