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Primes p with prime(p) - p + 1 and (p^2 - 1)/4 - prime(p) both prime.
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%I #9 Jan 17 2014 04:25:16

%S 17,31,41,43,61,71,83,103,109,173,181,211,271,349,353,541,661,673,743,

%T 811,911,953,971,1171,1429,1471,1483,1723,1787,2053,2203,2579,2749,

%U 3019,3299,3391,3433,3463,3727,3917,4003,4021,4049,4243,4447,4567,4657,4729,4801,4993

%N Primes p with prime(p) - p + 1 and (p^2 - 1)/4 - prime(p) both prime.

%C By the conjecture in A235919, this sequence should have infinitely many terms.

%H Zhi-Wei Sun, <a href="/A235920/b235920.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1) = 17 with prime(17) - 17 + 1 = 59 - 16 = 43 and (17^2 - 1)/4 - prime(17) = 72 - 59 = 13 both prime.

%t PQ[n_]:=n>0&&PrimeQ[n]

%t p[n_]:=PrimeQ[Prime[n]-n+1]&&PQ[(n^2-1)/4-Prime[n]]

%t n=0;Do[If[p[Prime[k]],n=n+1;Print[n," ",Prime[k]]],{k,1,1000}]

%Y Cf. A000040, A234695, A235727, A235806, A235914, A235919.

%K nonn

%O 1,1

%A _Zhi-Wei Sun_, Jan 17 2014