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Numbers n such that both A000203(n)-n-1 and A000203(n)-2*n-1 are prime numbers, and sigma(n)-2*n-1 > 5.
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%I #5 May 13 2013 01:54:11

%S 30,42,60,78,102,138,186,198,216,222,228,240,246,258,270,282,360,372,

%T 390,414,438,492,498,546,582,600,606,642,708,720,756,762,774,786,810,

%U 852,870,930,942,954,1002,1014,1020,1026,1038,1068,1086,1182,1266,1290

%N Numbers n such that both A000203(n)-n-1 and A000203(n)-2*n-1 are prime numbers, and sigma(n)-2*n-1 > 5.

%C The smallest term that is not multiple of 6 is 3472.

%H Charles R Greathouse IV, <a href="/A179945/b179945.txt">Table of n, a(n) for n = 1..10000</a>

%o (PARI) is(n)=my(s=sigma(n));s>2*n+6 && isprime(s-n-1) && isprime(s-n-n-1) \\ _Charles R Greathouse IV_, Feb 19 2013

%Y Subsequence of A175727.

%K nonn

%O 1,1

%A Alexey Galkin (fetch91(AT)gmail.com), Aug 03 2010