This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A244248 #9 Jun 22 2025 16:43:18
%S A244248 185,247,253,295,329,355,453,471,533,565,583,671,689,703,755,781,785,
%T A244248 815,841,989,1037,1099,1121,1159,1189,1207,1219,1329,1403,1441,1473,
%U A244248 1541,1555,1643,1661,1703,1751,1793,1797,1819,1821,1853,1921,1941,1957,2123,2189
%N A244248 Semiprimes whose binary representation, read in decimal, is prime.
%C A244248 Semiprimes in A036952.
%C A244248 Intersection of A001358 and A036952.
%H A244248 K. D. Bajpai, <a href="/A244248/b244248.txt">Table of n, a(n) for n = 1..10000</a>
%e A244248 a(1) = 185 = 5 * 37 which is semiprime. Binary representation of 185 = 10111001 which is prime.
%e A244248 a(2) = 247 = 13 * 19 which is semiprime. Binary representation of 247 = 11110111 which is prime.
%p A244248 with(numtheory):A244248 := proc() local a; a:=convert(n, binary); if bigomega(n)=2 and isprime(a) then RETURN (n) ; fi; end: seq(A244248 (), n=1..5000);
%t A244248 A244248={};Do[If[PrimeOmega[n]==2&&PrimeQ[FromDigits[IntegerDigits[n,2]]], AppendTo[A244248, n]], {n, 5000}]; A244248
%t A244248 Select[Range[2500],PrimeOmega[#]==2&&PrimeQ[FromDigits[IntegerDigits[#,2]]]&] (* _Harvey P. Dale_, Jun 22 2025 *)
%Y A244248 Cf. A000040, A001358, A036952, A242677.
%K A244248 nonn,base
%O A244248 1,1
%A A244248 _K. D. Bajpai_, Jun 23 2014