Yes Gareth, I must admit you're right! But "D-prime" reads in french "déprime" which means "low spirits" -- the mood I'm in after a night of thoughts : Is the <depressing> seq finite or not ;-? Best, É. -----Message d'origine----- De : math-fun-bounces@mailman.xmission.com [mailto:math-fun-bounces@mailman.xmission.com] De la part de Gareth McCaughan Envoyé : lundi 10 mars 2008 15:47 À : math-fun@mailman.xmission.com Objet : Re: [math-fun] A+B=C. Concatenate ABC On Monday 10 March 2008, Eric Angelini wrote:

What about D's (D-primes) giving two possible pre- decessors:

D'=22830 --> A=2 and B=28 or A=22 and B=8

I haven't thought about the actual problem at all, but I suggest that "D-prime" is just about the worst possible name for something whose defining characteristic is having multiple decompositions into simpler parts :-). -- g _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun