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 A096784 #11 Sep 08 2022 08:45:14 %S A096784 8,9,14,15,20,21,26,33,35,39,44,48,50,51,54,56,63,65,68,69,74,75,81, %T A096784 86,90,95,98,99,105,111,114,116,119,120,125,128,134,135,140,141,146, %U A096784 153,155,158,165,168,174,176,183,186,189,194,200,204,209,215,216,219,221 %N A096784 Numbers n such that both n and n+1 are composite numbers that sum up to a prime. %F A096784 Equals (A060254 -1)/2. %t A096784 Select[ Range[ 225], PrimeQ[ # ] == PrimeQ[ # + 1] == False && PrimeQ[2# + 1] == True &] (* _Robert G. Wilson v_, Jul 11 2004 *) %o A096784 (PARI) nextcomposite(k)=if(k<3,4,if(isprime(k),k+1,k)); %o A096784 {m=230;n=4;while(n<m,k=nextcomposite(n+1);p=n+k;if(k==n+1&&isprime(p),print1(n,","));n=k)} \\ _Klaus Brockhaus_, Jul 11 2004 %o A096784 (Magma)[n: n in [0..250]|not IsPrime(n) and not IsPrime(n+1) and IsPrime(2*n+1)] // _Vincenzo Librandi_, Dec 18 2010 %Y A096784 See A060254 for the primes 2n+1. %Y A096784 Cf. A096785, A096786, A096787, A096788. %K A096784 nonn %O A096784 1,1 %A A096784 _Lekraj Beedassy_, Jul 09 2004 %E A096784 Corrected and extended by _Klaus Brockhaus_ and _Ray Chandler_, Jul 10 2004