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 A086709 Primes p such that p-1 and p+1 are both divisible by fourth powers. 7

%I

%S 1249,2753,3727,4049,4801,5023,7937,10529,11503,12799,13121,15391,

%T 20897,21871,22193,23167,25759,28351,28751,31249,32561,33857,35153,

%U 37423,39041,42929,46817,47791,48751,49409,50383,51679,55889,58481,62047

%N Primes p such that p-1 and p+1 are both divisible by fourth powers.

%H Amiram Eldar, <a href="/A086709/b086709.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..2000 from Vincenzo Librandi)

%t f[n_]:=Max[Last/@FactorInteger[n]]; lst={};Do[p=Prime[n];If[f[p-1]>=4&&f[p+1]>=4,AppendTo[lst,p]],{n,8!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Oct 03 2009 *)

%t dfpQ[n_]:=Max[Transpose[FactorInteger[n]][[2]]]>3; Select[Prime[Range[ 6500]], dfpQ[#-1]&&dfpQ[#+1]&] (* _Harvey P. Dale_, May 11 2012 *)

%Y Cf. A046101, A075432, A086708, A089212.

%K nonn

%O 1,1

%A _Amarnath Murthy_, _Jason Earls_, Jul 28 2003

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Last modified May 12 07:28 EDT 2021. Contains 343821 sequences. (Running on oeis4.)