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A237039 Semiprimes of the form (2*p)^3 + 1, where p is prime. 6

%I #11 Jul 21 2021 11:30:51

%S 65,217,10649,195113,1191017,45882713,55742969,946966169,2106997769,

%T 2289529433,2548895897,10735357817,26946035993,54958685609,

%U 77199941513,131561576057,132495001193,440016501017,456888832409,623273556089,848202406697,966188398457

%N Semiprimes of the form (2*p)^3 + 1, where p is prime.

%H Amiram Eldar, <a href="/A237039/b237039.txt">Table of n, a(n) for n = 1..10000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Semiprime.html">Semiprime</a>.

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Semiprime">Semiprime</a>.

%F a(n) = (2*A237038(n))^3 + 1.

%e (2*2)^3 + 1 = 65 = 5*13 is a semiprime, so a(1) = 2.

%t L = Select[Range[5000], PrimeQ[#] && PrimeQ[(2 #)^2 - 2 # + 1] && PrimeQ[2 # + 1] &]; (2 L)^3 + 1

%t Select[Table[(2p)^3+1,{p,Prime[Range[1000]]}],PrimeOmega[#]==2&] (* _Harvey P. Dale_, Jul 21 2021 *)

%Y Cf. A001358, A046315, A081256, A096173, A096174, A237037, A237038, A237040.

%K nonn

%O 1,1

%A _Jonathan Sondow_, Feb 02 2014

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Last modified April 19 05:19 EDT 2024. Contains 371782 sequences. (Running on oeis4.)