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 A123370 #4 May 20 2013 16:10:19 %S A123370 3,5,13,173,699053,3301173438094347399730997933, %T A123370 15589350798196297794172638215640352209663280458413 %N A123370 Primes of the form (2^n + 7)/3. %C A123370 Corresponding n's are 1,3,5,9,21,93 (all but n=3 are of the form n=4m+1, m=0,1,2,5,23...). Cf. A123250 = primes of the form 2^n + 5. %t A123370 Select[(2^Range[0,1000]+7)/3,PrimeQ] (* _Harvey P. Dale_, May 20 2013 *) %Y A123370 Cf. A123250. %K A123370 nonn %O A123370 1,1 %A A123370 _Zak Seidov_, Oct 12 2006 %E A123370 a(7) from _Harvey P. Dale_, May 20 2013