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A089018 Smallest prime dividing the composite number consisting of A089017(n) successive 3's followed by a terminal 1.

%I A089018 #17 Jan 17 2019 13:44:06
%S A089018 17,673,307,19,523,607,181,199,31,1009,29,23,177943,61,312929,17,821,
%T A089018 353,363941,829,19,686269,31,1019,2761379,145501,1397023,28529353,47,
%U A089018 2543,17,439,23,59,70717063,15683,31,19,4555681103,10616546557,28759,83
%N A089018 Smallest prime dividing the composite number consisting of A089017(n) successive 3's followed by a terminal 1.
%H A089018 Factordb, <a href="http://factordb.com/index.php?query=%2810^n-7%29%2F3&amp;use=n&amp;n=1&amp;VP=on&amp;VC=on&amp;EV=on&amp;OD=on&amp;PR=on&amp;FF=on&amp;PRP=on&amp;CF=on&amp;U=on&amp;C=on&amp;perpage=200&amp;format=1&amp;sent=Show">(10^n-7)/3</a>
%H A089018 Makoto Kamada, <a href="https://stdkmd.net/nrr/3/33331.htm">Factorizations of 33...331</a>
%o A089018 (PARI) do(lim)=my(v=List());for(n=9,lim+1,if(ispseudoprime(10^n\3-2), next); forprime(p=7,,if(Mod(10,p)^n==7,listput(v,p); next(2)))); Vec(v) \\ tests numbers with A089017(n) <= m; _Charles R Greathouse IV_, Oct 23 2013
%K A089018 base,nonn
%O A089018 1,1
%A A089018 _Lekraj Beedassy_, Nov 04 2003
%E A089018 More terms from _Ray Chandler_, Nov 04 2003