A178012 Number of permutations of 2 copies of 1..n with no element e[i>=2]<e[1+floor((i-2)/2)] (2-way heap).

1, 2, 7, 44, 394, 5160, 95772, 2070282, 54033576, 1768770384, 74057667588, 3481862274120

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Crossrefs

Simple 2-way heap A056971.

Sequence in context: A111561 A000155 A077045 * A194018 A196793 A306880

Adjacent sequences: A178009 A178010 A178011 * A178013 A178014 A178015

Keyword

nonn

Author

R. H. Hardin, May 17 2010

Status

approved