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%I #18 Sep 08 2022 08:46:09
%S 6,13,48,176,2736,10928,174768,699056,11184816,727960800,2863311536,
%T 183355069408,2967356682528,11728124029616,188313058624992,
%U 12121838249371488,768906329487027264,3074457345618258608,196765296972010592800,3148244377723715041632
%N Sum of divisors of 2^prime(n)+1.
%C b-file computed with factorizations in Wagstaff link. a(166) corresponding to 2^983+1 is currently the first unknown term. - _Jens Kruse Andersen_, Sep 28 2014
%H Jens Kruse Andersen, <a href="/A247939/b247939.txt">Table of n, a(n) for n = 1..165</a>
%H Sam Wagstaff, <a href="http://homes.cerias.purdue.edu/~ssw/cun/">The Cunningham Project</a>
%F a(n) = A000203(A098640(n)). - _Michel Marcus_, Sep 27 2014
%p with(numtheory): A247939:=n->sigma(2^ithprime(n)+1): seq(A247939(n), n=1..20); # _Wesley Ivan Hurt_, Sep 27 2014
%t Table[DivisorSigma[1, 2^Prime[n] + 1], {n, 1, 20}]
%o (Magma) [SumOfDivisors(2^p+1): p in PrimesUpTo(100)];
%o (PARI) vector(50,n,sigma(2^prime(n)+1)) \\ _Derek Orr_, Sep 27 2014
%Y Cf. A000203, A069061, A098640.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Sep 27 2014
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