[seqfan] a(n) divides the concatenation
Eric Angelini
Eric.Angelini at kntv.be
Mon Apr 1 12:10:37 CEST 2013
Hello SeqFans (again, sorry to invade, last post of April First);
We look for the smallest integer a(n)
no yet present in S such that a(n) divides
the concatenation of a(n-1) and a(n).
S starts with a(1)=1
S is infinite, of course, and seems to
look like this (hope no bugs were introduced
by hand):
S=1,2,4,5,10,20,8,16,25,50,40,32,64,80,100,125,...
(we see for example here that 2 divides 12, that 4 divs 24, that 5 divs 45, that 10 divs 510, etc.)
Is there a pattern somewhere? Will the integer "3" appear at some point?
Is S interesting?
Best,
É.
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