A066222 Bisection of A001189.

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

Offset

0,2

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

Links

Table of n, a(n) for n=0..16.

Crossrefs

Sequence in context: A231592 A335345 A126965 * A080254 A190916 A161736

Adjacent sequences: A066219 A066220 A066221 * A066223 A066224 A066225

Keyword

nonn,easy

Author

N. J. A. Sloane, Dec 19 2001

Extensions

More terms from Frank Ellermann, Jan 01 2002

Status

approved