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%I #20 Apr 03 2023 10:36:13
%S 393,2105,2147,3155,5255,5357,25829,26231,28241,29447,33913,35719,
%T 39331,56513,58517,59519,79113,210653,212261,214271,215879,216683,
%U 219497,314147,315953,317759,318361,320167,321973,323779,326789,329197,520541,523547,529559,530561
%N Semiprimes formed by inserting a semiprime between the semiprime's ordered factors.
%H Charles R Greathouse IV, <a href="/A227942/b227942.txt">Table of n, a(n) for n = 1..10000</a>
%H Chris K. Caldwell and G. L. Honaker, Jr., <a href="https://t5k.org/curios/page.php?number_id=12444">Prime Curio for 13361</a>
%e a(2)=2105 because the semiprime 10 inserted between its ordered prime factors (2 and 5) is a semiprime.
%o (PARI) issemi(n)=bigomega(n)==2
%o list(lim)=my(v=List(), t); forprime(q=2, sqrtint(lim\10), forprime(p=2, min(sqrtint(lim\q), q), t=eval(Str(p, p*q, q)); if(t>lim, next(2)); if(issemi(t), listput(v, t)))); vecsort(Vec(v)) \\ _Charles R Greathouse IV_, Oct 04 2013
%Y Cf. A001358, A229480, A227943.
%K nonn,base
%O 1,1
%A _G. L. Honaker, Jr._, Oct 03 2013
%E More terms from _Farideh Firoozbakht_ Oct 04 2013
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