%I #5 Dec 26 2016 15:22:22

%S 1,9,75,763,9495,140151,2390479,46206735,997313823,23758664095,

%T 618884638911,17492190577599,532985208200575,17411277367391103,

%U 606917269909048575,22481059424730751231,881687990282453393919

%N Bisection of A001189.

%C a(n) is the number of sets of disjoint pairs that can be chosen from 2*n items. - Ron Zeno (rzeno(AT)hotmail.com), Feb 06 2002

%K nonn,easy

%O 0,2

%A _N. J. A. Sloane_, Dec 19 2001

%E More terms from _Frank Ellermann_, Jan 01 2002