%I #11 Sep 08 2022 08:46:09
%S 4,6,13,14,32,31,48,38,78,80,62,74,121,108,128,192,182,133,160,192,
%T 180,158,288,240,194,272,252,288,256,403,288,390,448,278,480,352,314,
%U 434,494,576,576,381,512,576,528,398,422,540,608,458,768,702,532,672
%N Sum of divisors of 2*prime(n)-1.
%C See A005382 (primes p such that sigma(2p-1) = 2p).
%H Jens Kruse Andersen, <a href="/A247787/b247787.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = sigma(A076274(n)) = A000203(A076274(n)).
%e For n = 3; prime(3) = 5, a(3) = sigma(2*5-1) = sigma(9) = 13.
%o (Magma) [SumOfDivisors(2*p-1): p in PrimesUpTo(2000)]
%o (PARI) vector(100,n,sigma(2*prime(n)-1)) \\ _Derek Orr_, Sep 25 2014
%Y Cf. A000203, A072057, A005382, A247788.
%K nonn,easy
%O 1,1
%A _Jaroslav Krizek_, Sep 24 2014