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%I #10 Oct 10 2019 00:34:52
%S 0,7,0,43,401,7,7649,823,4801,3607,82475249,7326743,41287201,89,
%T 23072849,7561,232930569601,2630513987207,8413597910449,
%U 398895185373143,297612001,558545864083,2988049,3400809163
%N Largest prime substring in 7^n (0 if none).
%H Vincenzo Librandi, <a href="/A046273/b046273.txt">Table of n, a(n) for n = 0..200</a>
%t lpss[n_]:=Module[{idn7=IntegerDigits[7^n]},Max[Select[Flatten[ Table[ FromDigits/@ Partition[idn7,i,1],{i,Length[idn7]}]],PrimeQ]]]; Array[ lpss,25,0]/.-\[Infinity]->0 (* _Harvey P. Dale_, Aug 17 2013 *)
%Y Cf. A046265.
%K nonn
%O 0,2
%A _Patrick De Geest_, Jun 15 1998
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