Yes, it's old hat. Even if I reinvented it. Thx, Zak >Пятница, 24 июня 2016, 16:42 +03:00 от Giovanni Resta <g.resta at iit.cnr.it>: > >On 06/24/2016 12:43 PM, Zak Seidov via SeqFan wrote: > >Could you make explicit what do you mean with Nx and N+ ? >I'm too old for riddles... > >Giovanni > > >-- >Seqfan Mailing list - http://list.seqfan.eu/