A178009 Number of permutations of 1..n with no element e[i>=2]<e[1+floor((i-2)/4)] (4-way heap).

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

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