Friends or maybe friends :　

　Jan Pedersen | Neil Sloane | Eric Weissstein | Eric Roosentaal | Matt Devos | Dan Archdeacon |　Kermit Rose | Simon Plouffe | Dean Hickerson | Noam Elkies | Karlis Podnieks | Derek Ball |　Jean-Charles Meyrignac | Randall Holmes | Richard K Guy | Steven Finch | Wolfgang Creyaufmueler |