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%I #9 Nov 18 2018 01:12:04
%S 2,3,7,7,31,31,211,211,211,211,2311,2311,6007,6007,6007,6007,102103,
%T 102103,3233231,3233231,3233231,3233231,17160991
%N Largest prime of the form a squarefree number + 1 where the prime divisors of the squarefree number are < n.
%C Conjecture: a(n)-1 has prime(n)-1 divisors. Subsidiary sequence: Number of primes of the form 2*p*q*r*...+1 where p, q, r, etc. are distinct odd primes < n.
%e a(13) = 6007 = 2*3*7*11*13 + 1, as 2*5*7*11*13 + 1, etc. are composite.
%t <<DiscreteMath`; <<NumberTheory`; Do[l = Select[Map[Times @@ #&, Subsets[Range[n]]], SquareFreeQ]; Print[Max[Select[Map[ #+1&, l], PrimeQ]]], {n, 1, 30}] (* _Ryan Propper_, Aug 13 2005 *)
%Y Cf. A092965, A060957.
%K nonn
%O 1,1
%A _Amarnath Murthy_, Mar 26 2004
%E More terms from _Ryan Propper_, Aug 13 2005
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