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 A175666 #21 Jan 27 2021 16:08:52 %S A175666 7,10,16,34,70,88,124,160,250,268,340,394,520,538,574,700,718,754,844, %T A175666 880,1078,1258,1294,1330,1474,1528,1780,1924,1960,1978,2050,2158,2230, %U A175666 2284,2428,2734,2860,3040,3058,3094,3148,3310,3670,3688,3868,4228,4318 %N A175666 Sum of Sophie Germain prime p and corresponding safe prime q=2p+1. %C A175666 For n > 1, numbers of the form 6k-2 such that Omega( (2k-1)(4k-1) ) = 2. - _Wesley Ivan Hurt_, Jun 28 2013 %C A175666 First semiprimes: 10,34,394,538,718,1294,2734. - _Zak Seidov_, Sep 07 2016 %H A175666 N. J. A. Sloane, <a href="/A175666/b175666.txt">Table of n, a(n) for n = 1..10000</a> %F A175666 a(n) = A005384(n)+A005385(n) = 3*A005384(n)+1 = (3*A005385(n)-1)/2. %o A175666 (PARI) is(n)=n%3==1 && isprime(n\3) && isprime((2*n+1)/3) \\ _Charles R Greathouse IV_, Jun 28 2013 %Y A175666 Cf. A005384, A005385. %K A175666 nonn %O A175666 1,1 %A A175666 _Zak Seidov_, Aug 05 2010