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A253906 Numbers n such that n^2 + 3 and n^3 + 3 are semiprime.

%I A253906 #32 Jan 29 2015 10:34:00
%S A253906 1,6,20,34,40,44,46,56,102,116,120,170,174,196,200,204,220,226,232,
%T A253906 234,252,260,262,294,296,320,334,336,344,346,358,360,382,386,392,412,
%U A253906 426,464,476,482,490,494,514,520,526,536,556,564,582,586,592,646,658,716
%N A253906 Numbers n such that n^2 + 3 and n^3 + 3 are semiprime.
%C A253906 All terms in this sequence, except a(1), are even.
%H A253906 K. D. Bajpai, <a href="/A253906/b253906.txt">Table of n, a(n) for n = 1..10000</a>
%e A253906 a(2) = 6;
%e A253906 6^2 + 3 = 39 = 3 * 13;
%e A253906 6^3 + 3 = 219 = 3 * 73;
%e A253906 Both are semiprime.
%t A253906 Select[Range[10^3], k = 3; PrimeOmega[(#^2 + k)] == 2 && PrimeOmega[(#^3 + k)] == 2 &]
%o A253906 (PARI)
%o A253906 issemiprime(q) = q>0 && bigomega(q)==2
%o A253906 select(n->issemiprime(n^2+3)&&issemiprime(n^3+3), vector(2000, n, n)) \\ _Colin Barker_, Jan 28 2015
%Y A253906 Cf. A001358, A242331, A108868.
%K A253906 nonn
%O A253906 1,2
%A A253906 _K. D. Bajpai_, Jan 24 2015