A178014 - OEIS

A178014

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

%I #3 Mar 31 2012 12:35:44

%S 1,3,18,189,3000,84060,2799360,148771080,8457799680,727583990400,

%T 53828906153760

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

%Y Simple 2-way heap A056971

%K nonn

%O 1,2

%A _R. H. Hardin_ May 17 2010