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A087713 Greatest prime factor of the product of the neighbors of the n-th prime. 1

%I

%S 3,2,3,3,5,7,3,5,11,7,5,19,7,11,23,13,29,31,17,7,37,13,41,11,7,17,17,

%T 53,11,19,7,13,23,23,37,19,79,41,83,43,89,13,19,97,11,11,53,37,113,23,

%U 29,17,11,7,43,131,67,17,139,47,71,73,17,31,157,79,83,13,173,29,59

%N Greatest prime factor of the product of the neighbors of the n-th prime.

%C a(n) = A006530((A000040(n)-1)*(A000040(n)+1)) = A006530(A006093(n)*A008864(n)) = A006530(A084920(n)).

%C Apparently a(n) = A024710(n) for n>4. - _Georg Fischer_, Oct 06 2018

%H Reinhard Zumkeller, <a href="/A087713/b087713.txt">Table of n, a(n) for n = 1..10000</a>

%e a(10) = A006530(A000040(10)^2 - 1) = A006530(29*29-1) =

%e A006530(840) = A006530(7*5*3*2^3) = 7.

%t FactorInteger[#][[-1,1]]&/@((#-1)(#+1)&/@Prime[Range[80]]) (* _Harvey P. Dale_, Oct 26 2019 *)

%o (Haskell)

%o a087713 = a006530 . a084920 -- _Reinhard Zumkeller_, Aug 27 2013

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Sep 28 2003

%E Definition clarified by _Harvey P. Dale_, Oct 26 2019

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Last modified May 17 12:55 EDT 2021. Contains 343971 sequences. (Running on oeis4.)