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%I #11 Jul 11 2021 20:00:37
%S 7,29,131,78139,3814697265661,7450580596923828179,
%T 4336808689942017736029811203479766845703247
%N Primes of the form 5^k + 2*k.
%C a(8) has 504 digits and is too large to be included.
%e 7 is a member of the sequence because 7 is a prime and 5^1 + 2*1 = 7.
%e 29 is a member of the sequence because 29 is a prime and 5^2 + 2*2 = 29.
%e 131 is a member of the sequence because 131 is a prime and 5^3 + 2*3 = 131.
%p a:=k->`if`(isprime(5^k+2*k),5^k+2*k,NULL): seq(a(k),k=1..1500);
%t Select[Table[5^k+2k,{k,80}],PrimeQ] (* _Harvey P. Dale_, Jul 11 2021 *)
%o (GAP) Filtered(List([1..700],k ->5^k+2*k),IsPrime);
%Y Cf. A299642, A299643, A297663, A303090.
%K nonn
%O 1,1
%A _Muniru A Asiru_, Apr 18 2018
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