This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A066222 #5 Dec 26 2016 15:22:22 %S A066222 1,9,75,763,9495,140151,2390479,46206735,997313823,23758664095, %T A066222 618884638911,17492190577599,532985208200575,17411277367391103, %U A066222 606917269909048575,22481059424730751231,881687990282453393919 %N A066222 Bisection of A001189. %C A066222 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 A066222 nonn,easy %O A066222 0,2 %A A066222 _N. J. A. Sloane_, Dec 19 2001 %E A066222 More terms from _Frank Ellermann_, Jan 01 2002