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%I #7 May 31 2022 06:47:38
%S 19,421,10039,95383574161,2384331073699,
%T 1925929944387235853055979210606894889560480247048440342330377620014353281101
%N Primes of the form (3^n + 5^n)/2^3 = A074606(n)/8.
%C Corresponding numbers n such that (3^n + 5^n)/8 is prime are listed in A122853. All these numbers are primes. - _Alexander Adamchuk_, Sep 14 2006
%C The next term is too large to include. - _Alexander Adamchuk_, Sep 14 2006
%F a(n) = (A122853(n)^3 + A122853(n)^5)/8. a(n) = A074606[A122853(n)]/8 = A081186[A122853(n)]/4. a(n) = A079773[A122853(n)]. - _Alexander Adamchuk_, Sep 14 2006
%t Do[f=5^n+3^n;If[PrimeQ[f/2^3],Print[{n,f/2^3}]],{n,1,1231}] (* _Alexander Adamchuk_, Sep 14 2006 *)
%Y Cf. A074706, A122853, A081186, A079773, A121824, A121877, A005058, A005059, A121938, A109347.
%K nonn
%O 1,1
%A _Zak Seidov_, Sep 10 2006
%E More terms from _Alexander Adamchuk_, Sep 14 2006
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