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 A053177 #24 Apr 01 2019 14:10:23
%S A053177 15,27,35,39,63,75,87,95,119,123,135,143,147,159,195,203,207,215,219,
%T A053177 255,275,279,299,303,315,327,335,363,387,395,399,423,447,455,459,483,
%U A053177 515,527,539,543,555,567,615,623,627,635,663,675,695,699,707,735,747
%N A053177 Odd composite k such that (k-1)/2 is prime.
%C A053177 Composite numbers produced in A053176.
%H A053177 Michael De Vlieger, <a href="/A053177/b053177.txt">Table of n, a(n) for n = 1..10000</a>
%H A053177 R. P. Boas & N. J. A. Sloane, <a href="/A005381/a005381.pdf">Correspondence, 1974</a>
%F A053177 From the composite, subtract 1, divide by 2 and result is a prime.
%e A053177 a(3)=35 and 35-1=34, 34/2=17, prime.
%t A053177 Select[2 Prime@ Range@ 74 + 1, CompositeQ] (* _Michael De Vlieger_, Jul 13 2015 *)
%t A053177 Select[Range[1,801,2],CompositeQ[#]&&PrimeQ[(#-1)/2]&] (* _Harvey P. Dale_, Apr 01 2019 *)
%o A053177 (PARI) main(size)={my(v=vector(size),i,t=1);for(i=1, size, while(isprime(2*prime(t)+1), t++); v[i]=2*prime(t)+1;t++;);return(v)} /* _Anders Hellström_, Jul 13 2015 */
%Y A053177 Cf. A053176, A005385, A005382, A259978.
%K A053177 easy,nonn
%O A053177 1,1
%A A053177 _Enoch Haga_, Feb 29 2000
%E A053177 Definition clarified by _Peter Munn_, Oct 26 2017