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Number of permutations of 1..n with no element e[i>=2]<e[1+floor((i-2)/5)] (5-way heap).
3

%I #11 May 28 2016 10:24:04

%S 1,1,1,2,6,24,120,360,1680,10080,72576,604800,3326400,26611200,

%T 259459200,2905943040,36324288000,290594304000,3293402112000,

%U 44460928512000,675806113382400,11263435223040000,118266069841920000,1734569024348160000,29921315670005760000

%N Number of permutations of 1..n with no element e[i>=2]<e[1+floor((i-2)/5)] (5-way heap).

%H Alois P. Heinz, <a href="/A178010/b178010.txt">Table of n, a(n) for n = 0..484</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/D-ary_heap">D-ary heap</a>

%Y Simple 2-way heap A056971.

%Y Column k=5 of A273693.

%K nonn

%O 0,4

%A _R. H. Hardin_, May 17 2010

%E a(0), a(21)-a(24) from _Alois P. Heinz_, May 27 2016