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%I #19 Sep 24 2023 03:56:02
%S 3,5,3,13,3,5,3,37,3,3,61,73,3,5,3,3,3,11,7,3,5,157,3,3,193,3,5,3,7,3,
%T 11,3,3,277,3,7,313,5,3,3,3,19,3,5,3,397,421,5,3,457,3,3,13,3,3,3,3,
%U 541,7,3,5,3,613,3,5,3,661,673,3,17,3,3,733,5,757,3,3,13,3,19,3
%N Least prime divisor of 2*prime(n)-1.
%H Harvey P. Dale, <a href="/A023585/b023585.txt">Table of n, a(n) for n = 1..1000</a>
%t FactorInteger[#][[1,1]]&/@(2Prime[Range[90]]-1) (* _Harvey P. Dale_, Oct 08 2017 *)
%o (PARI) a(n) = factor(2*prime(n)-1)[1, 1]; \\ _Michel Marcus_, Oct 01 2013
%Y Cf. A020639, A076274.
%K nonn
%O 1,1
%A _Clark Kimberling_
%E Definition edited by _Michel Marcus_, Oct 01 2013
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