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%I #18 Nov 05 2023 11:02:16
%S 25,34,38,57,93,118,133,145,177,201,205,213,218,298,334,361,381,394,
%T 446,501,633,694,698,842,865,878,898,921,1114,1141,1226,1285,1293,
%U 1465,1513,1654,1713,1726,1761,1857,1893,1941,1981,2018,2041,2217,2306,2426,2433,2577,2581,2734,2746,2901,2973,3133,3193,3214,3241,3386,3578,3661,3693,3746,3754,3777,3826,3957
%N Numbers k with the property that k, k+1 and 2*k+1 are all semiprimes.
%C Numbers k such that 2k+1 is a semiprime and the sum of two consecutive semiprimes (k and k+1).
%H Zak Seidov, <a href="/A188059/b188059.txt">Table of n, a(n) for n = 1..1309</a> (terms < 200000)
%F Equals A111153 intersect A070552. - _M. F. Hasler_, Mar 20 2011
%e 25 is a term: k = 25 = 5*5, k+1 = 26 = 2*13, 2k+1 = 51 = 3*17.
%t Select[Range[4000],Union[PrimeOmega[{#,#+1,2 #+1}]]=={2}&] (* _Harvey P. Dale_, May 11 2012 *)
%Y Cf. A001358 (semiprimes).
%Y Cf. A176896 (safe semiprimes), A111153 (Sophie Germain semiprimes), A070552.
%K nonn
%O 1,1
%A _Zak Seidov_, Mar 20 2011