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 A216075 #23 Apr 06 2018 14:21:37 %S A216075 3,4,9,15,16,21,37,40,47,51,55,56,71,74,103,108,111,114,118,119,130, %T A216075 161,165,180,184,185,188,195,200,208,219,227,231,232,238,239,240,255, %U A216075 267,272,273,274,278,290,292,317,326,340,354,359,381,388,392,396,416 %N A216075 Numbers n such that 2*prime(n) - prime(n+1) is prime. %C A216075 Corresponding values of 2*prime(n) - prime(n+1) are in A215808. %H A216075 Zak Seidov, <a href="/A216075/b216075.txt">Table of n, a(n) for n = 1..1000</a> %t A216075 f[n_]:=(2Prime[n]-Prime[n+1]); Select[Range[1000],PrimeQ[f[#]]&] %t A216075 Position[Partition[Prime[Range[500]],2,1],_?(PrimeQ[2#[[1]]-#[[2]]]&), 1,Heads->False]//Flatten (* _Harvey P. Dale_, Apr 06 2018 *) %o A216075 (PARI) list(lim)=my(v=List(),n,p=2); forprime(q=3,, if(n++>lim, return(Vec(v))); if(isprime(2*p-q), listput(v,n)); p=q) \\ _Charles R Greathouse IV_, May 22 2017 %Y A216075 Cf. A215808. %K A216075 nonn %O A216075 1,1 %A A216075 _Zak Seidov_, Sep 06 2012