A066222 Bisection of A001189.

1, 9, 75, 763, 9495, 140151, 2390479, 46206735, 997313823, 23758664095, 618884638911, 17492190577599, 532985208200575, 17411277367391103, 606917269909048575, 22481059424730751231, 881687990282453393919

Offset: 0

Author

N. J. A. Sloane, Dec 19 2001

Keywords

• nonn
• easy

Comments

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

Extensions

More terms from Frank Ellermann, Jan 01 2002