A169583 - OEIS

%I #11 Nov 10 2017 16:00:42

%S 1,4,12,19,47,59,115,167,217,251,306,348,414,618,630,662,809,1077,

%T 1138,1218,1670,1876,2272,2680,2869,3402,3633,4242,4353,4661,5255,

%U 6463,6596,6986,8543,8870,8992,9340,9444,10265,11544,11921,12449,13887,14031

%N n-th prime*8-7 is the square of a prime.

%H Harvey P. Dale, <a href="/A169583/b169583.txt">Table of n, a(n) for n = 1..350</a>

%e 1 is in the sequence because 1st prime*8-7=(2nd prime)^2;

%e 4 is in the sequence because 4th prime*8-7=(4th prime)^2;

%e 12 is in the sequence because 12th prime*8-7=(7th prime)^2.

%t Select[Range[15000],PrimeQ[Sqrt[8Prime[#]-7]]&] (* _Harvey P. Dale_, Nov 10 2017 *)

%o (PARI) isok(n) = issquare(sq=prime(n)*8-7) && isprime(sqrtint(sq)); \\ _Michel Marcus_, Apr 15 2014

%Y Cf. A000040, A001248, A055469, A118940.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Mar 01 2010

%E Corrected (1077 inserted) and extended by _R. J. Mathar_, Jun 04 2010