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%I #25 Dec 06 2022 07:56:43
%S 2,5,19,263,373,1033,65551,123833,283553,292993,2197633,5778673,
%T 12795193,10500613,19980283,32213033,36978853,72494813,140724953,
%U 164119063,183105509,193710277,320210941,450065801,268354393,496922891,506906473,1333406021
%N Primes arising in A064205.
%H Amiram Eldar, <a href="/A055813/b055813.txt">Table of n, a(n) for n = 1..5000</a> (terms 1..276 from Michel Marcus)
%F a(n) = A007503(A064205(n)). - _Amiram Eldar_, Dec 06 2022
%e a(3) = 19 since, for A064205(3) = 8, sigma(8)+tau(8) = 15+4 = 19, a prime number. - _Michael De Vlieger_, Dec 17 2016
%t Select[Table[Total@ Map[DivisorSigma[#, n] &, {0, 1}], {n, 10^7}], PrimeQ] (* _Michael De Vlieger_, Dec 17 2016 *)
%o (PARI) lista(nn) = for (n=1, nn, if (isprime(p=sigma(n) + numdiv(n)), print1(p, ", "))); \\ _Michel Marcus_, Dec 18 2016
%Y Cf. A007503, A064205.
%K nonn
%O 1,1
%A _Labos Elemer_, Nov 22 2001
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